Writers of Pro Football Prospectus 2008

18 Aug 2007

Tarik Glenn and The Blind Side

Sometime after the NFL draft I finally got around to reading Michael Lewis' excellent book The Blind Side. The book tells two interwoven stories: the amazing personal story of Michael Oher and the dramatic shift in the NFL that made him, a left tackle product, so intriguing. Basically since the arrival of Lawrence Taylor, teams have been obsessed with attacking and protecting quarterbacks from the blind side.

As a Colts follower, the book particularly resonated because the Colts had recently traded away their 2008 first-round pick for the right to select Tony Ugoh. At the time, the selection marked 2007 as the last season for long-time tackle Tarik Glenn, the starter at left tackle for basically Peyton Manning's entire career.

I thought the lack of media coverage of this move was amazing, particularly given the Sturm und Drang that surrounded the Eagles selection of Kevin Kolb. The Colts effectively declared that their Pro Bowl left tackle would not be re-signed after this upcoming season, and nobody seemed to blink. Clearly the media was still fixated on skill position players, while the league was focusing on linemen. Three of the top five picks in that draft were players who are supposed to either attack or defend the quarterback's blind side.

Since the draft, Glenn decided to retire immediately. A Colts offense that planned to return all their Super Bowl starters now is protecting Manning's blind side with an untested rookie. A year ago, the Colts survived the departure of their Pro Bowl running back, Edgerrin James. The assumption now seems to be that as long as the Colts have Manning (or at least Manning, Marvin Harrison, and Reggie Wayne), then the offense will be a juggernaut.

Running back and left tackle, however, are not the same position. Everyone at Football Outsiders, save me, predicted a year ago that the Colts would not miss James much if at all. But, we often emphasize the importance of offensive linemen. If Manning cannot feel comfortable with the rush from behind, he'll get happy feet and cease to be a dominant player. If the left tackle cannot hold the corner on the stretch play to the left, the Colts run attack will stall.

Part of the reason for calm is likely the sense that Glenn was not a dominant player. That may be the case, but more importantly, Glenn was never dominated. He was a second-tier tackle in the dominant era of left tackles. A contemporary of Walter Jones, Jonathan Ogden, and Orlando Pace, Glenn was easy to overlook as a very good but not great tackle for almost a decade. Glenn has been a solid pass protector but also excelled in run blocking, the other essential attribute of a quality left tackle.

Glenn's true value is difficult to measure due to the Colts unique system and the lack of offensive line statistics. The Colts do not require their offensive linemen to hold their blocks as long, and the heavy reliance on the stretch play in the run game emphasizes agility over brute force. As a result, traditional scouting can fail to accurately analyze Glenn's ability.

Statistically, the best we have is adjusted line yards to measure run blocking prowess. The stat is imperfect at identifying the ability of an individual offensive lineman. Still, it is worth noting that the Colts ranked first in runs behind left tackle last season and in the top six in five of the past seven seasons. They have ranked in the top 10 in runs around left end in six of the past seven seasons. The one exception was James' post-ACL season when the Colts' rushing offense was atrocious in general. (Pass protection stats are even sparser, but it should be noted that our game-charting project only ascribed two sacks to Glenn all season.)

One other place to look for Glenn's impact is the 2003 season where Glenn missed six games, the only injury of his career. Thanks to the premium DVOA database (remember, now available for purchase), we can see how the Colts performed in the games he missed. Glenn missed the games in Week 6, 8, 10, 11, 12, and 13. For those six games, the Colts average offensive DVOA was 17.4%. In the Colts' other ten games, their average offensive DVOA was 16.2%.

While those numbers are encouraging to Colts' fans, a large part of the discrepancy was a disastrous season-opening game against the Browns where the Colts offense posted a DVOA of -30.4%. Eliminate that game, and the Colts averaged 21.3% in the other nine Glenn games. Eliminating that game may not seem fair, but if memory serves (and I could be wrong), the Colts switched to a predominately no-huddle offense after the Cleveland game.

Even so, the four percent difference is hardly a massive discrepancy. Maybe the Glenn retirement will be just a minor nuisance easily overcome by Manning, et al. Also, while Ugoh is unproven, he is not exactly a street free agent. He is a second-round pick who the Colts obviously loved even before they knew Glenn was retiring. By all accounts, Ugoh could develop into an excellent left tackle in his own right.

Still, Glenn was a very good player for a long time at a crucial position. The Colts ability to overcome the loss of James is Exhibit 1 on the fungible nature of running backs. If the Colts don't miss a beat without their Pro Bowl left tackle, what does that say about the fungible nature of left tackles? Or does the dominance of Manning and astute drafting by Bill Polian make the Colts a poor team to use for a league-wide principle? No matter what, the Colts' offensive fortunes without Glenn are a story worth watching and perhaps a data point in the continuing struggle to determine the relative worth of offensive positions.

Posted by: Ned Macey on 18 Aug 2007

8 comments, Last at 20 Aug 2007, 3:57pm by doktarr


by Yaguar (not verified) :: Sat, 08/18/2007 - 2:23am

Very well-written. I don't have a strong opinion on what will happen to the Colts without Glenn. Last year, I thought losing Wayne would hurt us, but losing Edge and drafting a new RB would not. This year, I really don't know.

I believe that the LG, RG, and RT in the Colts offense are pretty fungible. I would not be worried if Jake Scott couldn't play. Losing Glenn will hurt, but I'm not sure how much. And I don't think we'll necessarily notice if it does. The loss of Glenn could mean that Manning beats Brady and Palmer by "only" 50 DPAR instead of 80.

The thing is, that's a lot. 30 DPAR is about what Chad Johnson was worth last year. And Tarik Glenn might be worth as much as Chad Johnson, or more, even. We really don't know, and that's kind of the point of the post.

One thing I feel like I should mention:
"Pass protection stats are even sparser, but it should be noted that our game-charting project only ascribed two sacks to Glenn all season."

It's worth knowing that Manning took only 14 sacks all season. When you say he was directly accountable for 1/7 of the Colts' team sacks, it certainly doesn't look like he's a magic blind-side shield or anything.

by Noble (not verified) :: Sat, 08/18/2007 - 10:17am

Well, the opposite side to the 1/7th argument is, how ofted did Glenn play relative to the other OL positions?

by Sisyphus (not verified) :: Sat, 08/18/2007 - 11:11am

I would generally agree that the potential for Glenn's retirement to have an impact is greater the absence of James last season. The issue though has as much to do with breaking the continuity of that line as it does with starting a rookie.

To the advantage of the Colts they have Howard Mudd, perhaps one of the best offensive line coaches in the NFL. Also the overall experience of the line and Peyton Manning is such that this may be a relatively minor issue as the season progresses.

by Ben (not verified) :: Sat, 08/18/2007 - 12:39pm

I think it will be difficult to draw conclusions on the importance of LT as a whole based on this change. You may be able to assess Tony Ugoh vs. Tarik Glenn, as most of the other variables stay constant in the Colts offense, but I don't know how this relates to the rest of the league.

What I think will be interesting is how the Colts try to protect the rookie, if they do at all. The comparison that I am interested in would be how many runs to LT and LE compared to last year. How many blockers stay in in pass protection compared to last year. How does it change over the course of the year? This data will definitely start to answer the Glenn vs. Ugoh question

by starzero (not verified) :: Sat, 08/18/2007 - 1:19pm

thank you for this. as a colts fan i've always felt they are underappreciated. i wonder if ugoh can manage fewer false starts than glenn, and whether that will make a difference.

by johnt (not verified) :: Sat, 08/18/2007 - 7:31pm

Well, it seems likely that they had some inkling that Glenn's retirement was coming and so choosing Ugoh may not be a matter of loving him as much as knowing there was a good chance they needed the best LT prospect they could get for this season to not be a disaster (actually, it kind of mirrors the Giants situation with Petitgout and Manning Jr.).

Keeping the TE in is an unappealing option in their standard formation because Dallas Clark is a TE in name only. So they're either going to have to go to 2TE base more, which will waste their 1st round pick this year, keep Clark in more, which is hardly a good use of his talents, or hope Ugoh can hold his own.

They have too much talent and Manning is too good at compensating for weaknesses for them to not be a dominant offense. I think it'll mostly be felt in a "what could have been" way - they had to play without a real #3 WR last year, this year having Gonzalez will be offset by losing Glenn so things may wind up looking similar. Especially since Manning's new 30 5-yard pass drives fit perfectly with hiding the rookie LT's flaws.

by Bobman (not verified) :: Sun, 08/19/2007 - 4:33am

I, too, was surprised at the collective media yawn over Glenn's retirement. I generally regard him as a half notch below the three big names noted above. Not much, really. Though there's that TD-stealing false start in the Pittsburgh playoff game 2 years ago I still can't forgive him for. grrrrr.

Looking at how they drafted Clark in the 1st round when they still had a pro bowl caliber TE but in his last contract year, I was a bit puzzled back then. I understood it, but surely they needed a defender more, right? Well, Polian proved to be smarter than I and it's not the first time, nor will it be the last.

I think the Ugoh draft mirrors the Clark draft. Plus, Glenn, having worked his whole professional life at Indy, may well have tipped his hand to mgmt. Hell, the guy repaid the balance of his signing bonus like the next week, so he was super prepared to leave and do it right. I think drafting Ugoh was a combination of looking out to next year as well as "hey, it might happen sooner."

Plus, after the preseason a couple years ago when Glenn could not participate because he just could not get his weight down, did anybody NOT see this coming? Once that happened I figured he was just one banana split form retirement, or failing a physical, or something. And didn;t a rookie fill in for him a few seasons ago (Frietas?) just fine? Much as I like Glenn, I think he'll prove to be as fungible as Edge.

Now how will Ugoh do? I'm sure they'll be fine; different, but fine. The offense is rarely static and is ever evolving (despite the fact that some people would prefer to see 2004 repeated a few more times). Mudd is a stud. I'm more concerned about spelling Addai by giving someone competent 150 rushes or so and getting BOTH Clark and Gonzo enough opportunities.

Say Ugoh is a solid step down from Glenn for his first year... what does that mean? 4 more sacks? (for a season total of 18!) More dumpoffs rather than Manning holding the ball longer and waiting for someone to get open deep? Tom Moore is a stud as well and they'll adapt fine; by week 12 will be firing on all cylinders. Just slightly diferent cylinders than we've become used to.

by doktarr (not verified) :: Mon, 08/20/2007 - 3:57pm

I don't know if this will really help us in the overall effort to separate credit for offensive success, but it should make for a very interesting data point on the whole "Manning's incredible read-and-release" versus "the Colts' underrated O-line" question. As discussed in this thread from last year.

My guess is that Bobman is right, and that by midseason Ugoh will be doing a good enough job to let the offense shine. At which point the aformentioned debate will not go away, because you could argue that Poilan did a great job finding a replacement (which may be true).

Broncos:RB::Pats:WR::Colts:OL? Well, I hope so.