In Week 15, the Eagles got rolled by the Minnesota Vikings, in what was one of the more disappointing losses of the season. On the Vikings' first TD, they came out in a 3-WR set. The Eagles stayed in their base D, which forced Patrick Chung to cover Greg Jennings man to man in the slot:
Chung had help over the top on that side of the field from Nate Allen, and he had help over the middle from DeMeco Ryans, but what this defense didn't account for was for the slot receiver to run 50 yards down the field and all the way across it to make a catch. For that to happen, the QB would have to have a boatload of time, and because Matt Cassel was able to step away from pressure from Trent Cole and Fletcher Cox, Jennings had time to blow right past Chung.
Look at how open Jennings got against Chung on the play. This is a solid 2-3 yards of separation:
Ideally, you would like for your safeties to be able to run with slot receivers, but most can't. Chung couldn't cover slot receivers one on one, and probably shouldn't have been asked to do so. The result of this play was of course a 57 yard TD and a 7-0 deficit.
In Week 17, with the division on the line and the Eagles clinging to an 8 point lead with less than 4 minutes to play on 4th and 9, the Cowboys needed a 1st down conversion to keep the game alive.
They used pre-snap motion, which exposed Chung man to man on Dez Bryant with absolutely no safety help behind him, as the Eagles were sending the house at Kyle Orton.
I can actually remember saying "Touchdown" out loud just before the ball was snapped. And sure enough, Orton hit Bryant over the middle, Chung missed the tackle, and Bryant ran in for the easy score. Again, Chung had no chance against Bryant, and probably shouldn't have been expected to cover a WR of his caliber one on one.
Malcolm Jenkins is a far better cover safety. At Ohio State he was a CB and was the 14th overall pick in the 2009 draft, but converted to safety after his rookie season. It's probably not even fair to call him a true safety. He's more like a safety / slot CB hybrid. When the Saints went to their nickle defense last season, they would often bring in a 3rd safety, and Jenkins would play the slot. Because of his excellent versatility, Jenkins was asked to do more difficult things than a typical safety.
In case you don't recognize him, that would be Larry Fitzgerald that Jenkins is manning up at the goal line. If it were Patrick Chung, you can be fairly certain that Carson Palmer would have checked to Fitzgerald, but on this play, he threw an incomplete fade to the receiver at the bottom of the screen. Why? Because Jenkins is respected as a legitimate cover safety player. Sheil Kapadia of Birds 24/7 has more examples of the difficult things the Saints asked Jenkins to do last season.
That brings us to ProFootballFocus' (PFF) player rankings. PFF is an incredibly valuable service for its raw data. There aren't many places where you can find how many times a linebacker dropped into coverage, or how long a QB held onto the ball on average before he threw. PFF provides that kind of data, which is extremely valuable. However, many of their stats are useless, without context. For example, it has been pointed out that Jenkins gave up 486 passing yards on balls thrown his way in 2013, which was 2nd most among safeties in the NFL.
However, that ignores context. When a player like Jenkins is covering guys like Larry Fitzgerald in the slot, of course he's more likely to fail than a safety playing deep middle in Cover 3. The Saints gave Jenkins difficult responsibilities because they trusted that he could handle them better than anyone else on their team. The side-effect of that, however, is that a site like PFF isn't going to adequately account for the degree of difficulty. They'll simply chalk up a poor number, then stand behind it like it's the end-all be-all measure of that player's worth.
Jenkins received a -6.0 grade (65th out of 86 safeties) from PFF last season. Patrick Chung was right in the same neighborhood, at -7.0 (71st out of 86). However, when you watch the two play, a novice can easily identify that the skill levels of Chung and Jenkins aren't even remotely close. Jenkins will be a significant upgrade in the Eagles' pass defense. Ignore the noise.
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