Domo: Tight end group is offense's biggest strength

A COACH MUST play to his strengths. But if you're Doug Pederson and offensive coordinator Frank Reich, what are they right now?

Is it an offensive line that is likely to lose its right tackle for 10 games for his second PED offense in three years, and might have to throw a third-round rookie to the wolves at left guard?

Is it a wide receiving corps that is starting to look as if it might be no better than it was a year ago, when it had only one player with more than 27 catches?

Is it a running back group whose best player has durability issues and whose second-best player is 33 years old and is a better receiver than he is a runner?

Right now, the Eagles' best offensive unit, and perhaps their best hope for creating problems for opposing defenses this season, is tight end, with Zach Ertz, Brent Celek and Trey Burton.

The Eagles have been amping up three-tight sets in training camp and used one on Ryan Mathews' 5-yard first-quarter touchdown run Thursday night in their preseason win over the Tampa Bay Bucs.

Ertz, Celek and Burton lined up on the right side of the line and paved the way for Mathews' dash into the end zone. Burton, probably the least accomplished blocker of the three, did an excellent job blocking down on a linebacker at the line of scrimmage, then moving to the second level and sealing off safety Bradley McDougald.

"It was the first stage of implementing the three tight ends," said Ertz, who had a career-high 75 catches last season, and, along with slot receiver Jordan Matthews, became quarterback Sam Bradford's go-to guys. Ertz and Matthews combined for 51 receptions in the Eagles' last three games last season.

"We'll see how teams game-plan for it each week," Ertz said. "We think it could be a big staple of the offense. We have three really talented tight ends, in my opinion. I think that package is going to grow each and every week."

Ertz, Celek and Burton all are excellent receivers. But the key will be their ability to block.

If they can block as well as they did on Mathews' touchdown run, then opposing defensive coordinators will have a difficult decision to make as far as whether to stay in their base defense or bring in extra defensive backs and/or linebackers.

Celek, who has 371 career receptions and has caught 55 or more passes three times, is one of the league's best blocking tight ends.

Ertz is a receiver first, but has worked hard to turn himself into a competent blocker.

At 6-3 and just under 240 pounds, Burton is the smallest of the three. He's a former wide receiver and quarterback, who has been a key member of the special teams the last two years. His development as a blocker will be the key to the success of the Eagles' three-tight end sets.

"Trey, that's what we need out of him," Reich said of Burton's nice blocking on Mathews' touchdown run.

"He did a really nice job. He can't just be a receiving tight end. Because otherwise, teams won't treat (the three-tight end personnel grouping) as three tight ends. So we have to be able to line up in those heavy sets, and he has to block like a tight end, which he's doing."

"We run that play a lot in practice," Burton said. "The coaches have done an unbelievable job of telling us what to expect. They did what we expected and it worked."

It's not uncommon for offenses to employ two-tight end sets. Chip Kelly used them a lot with the Eagles the last three years.

Bradford had a 101.6 passer rating and a 73.7 completion percentage last season throwing out of two-tight end formations.

Most teams use three-tight end sets only in short-yardage and goal-line situations.

Last year in Kansas City, where Pederson served as Andy Reid's offensive coordinator, the Chiefs used two-tight end sets on 222 of 955 offensive plays (23.2 percent). They used three-tight end sets with Travis Kelce, Demetrius Harris and either James O'Shaughnessy or Brian Parker 78 times, which was among the most in the league.

"When I was in San Diego (as the Chargers' quarterbacks coach in 2013 and their offensive coordinator in 2014-15), we always had a three-tight end package because we had Antonio Gates and Ladarius Green, and then we had two blocking tight ends," Reich said. "So we would use combinations of those three guys to create mismatches for our tight ends."

What Ertz, Celek and Burton give the Eagles is not two, but three, tight ends who can get open and catch the ball.

"When you have three tight ends in the game, (the defense) always is going to be in base defense," Reich said. "There's not a fifth defensive back. So, now, when you've got a guy like Trey Burton, who I could argue runs routes as good as a (wide) receiver, that's a mismatch for us. Zach doesn't have a wide-receiver body or run wide-receiver routes. But he's a great route-runner and creates a different kind of mismatch.

"Or sometimes, depending on what part of the game it is, you have three tight ends, and sometimes, if it's like third-and-1, (the defense) will go with what we call 'beast.' They'll bring in an extra linebacker. Now, you really have mismatches all over the field.

"That's part of our job as coaches to understand how personnel groups-wise and formationally, how you can create those mismatches."

Eagles defensive coordinator Jim Schwartz said it's very difficult for a defense to match up against three multidimensional tight ends as the Eagles have.

"If you have three guys that are just stone-cold blockers and they can't run a route, it's pretty easy to defend," he said. "And if you have three guys that are pass receivers and they can't block a soul, it's pretty easy to defend.

"But if you have guys that can do both and they can give you a lot of different looks and they can be in three tight ends, it might be a short-yardage-looking offense or it might be a three-wide-receiver-looking offense. All three of those guys have the capability of doing it. It just forces you to be able to match up."

Nobody is happier about the Eagles using three-tight end sets than the third tight end - Burton. He earned his keep primarily on special teams, playing only 63 offensive snaps last season. Kelly used three-tight end sets last season just 16 times.

"I have no clue how much we're going to use it," Burton said. "Our job (as players) is just to play. Obviously, I'd love to have them use it every single play. But that's probably not going to happen.

"There are things I have to continue to work on in order for them to want to put me out there."