The 2007 fifth-round draft choice out of Cincinnati enjoyed a career season in 2009 with Donovan McNabb under center. Celek caught 76 passes for 971 yards with eight touchdowns, but has not seen the same productivity in the three-plus seasons since. From 2010-12, Celek played in 47 of 48 games, averaging 53.7 receptions and 668.7 receiving yards, with 10 touchdown receptions.
So what has changed for Celek since McNabb was traded to Washington in 2010? With a focus on becoming a better blocker, he thinks it has nothing to do with the quarterback, but how each defense has played against the Eagles over the past few seasons and into this season with Kelly's high-octane offense.
"I don't think it has anything to do with who is quarterback," Celek said about his statistical decline. "I think it just depends on what teams are giving us. They are playing a lot of man coverage right now. Obviously, we are running the ball really well, so I don't know. There are really a lot of different factors."
Celek added that he does not care so much about his statistics.
"I mean, I've become a better blocker over the years," he said. "It's more of a technique thing when you are blocking guys this big, and I've really gotten better at it. I've just focused on getting better overall, and I think that is one area where I was able to improve on. It's something I did well in college and I just had to get back to it."
This season, Celek has played 410 snaps, while Ertz has been in the game for 183 snaps, yet the two have similar receiving statistics. Celek has been targeted 23 times with 12 receptions and 197 yards, with two touchdowns; Ertz has been targeted 22 times with 13 receptions and 196 yards, with no touchdowns.
Although Celek has seen a sharp decline in the amount of times he has been targeted this season compared with past seasons, Kelly said it is not by design, but rather the decision of each quarterback based on the designed play.
"It just depends on where our quarterback is distributing the football, but it's not like we are calling and saying don't throw it to the tight end," Kelly said. "He had a couple of big catches the last time we played the Giants, had a touchdown catch against them, had a big third-down catch against them on a crossing route. We expect that he can be a matchup problem at times if you're going to consistently play man, because he is such a big target."
Even though the Eagles used their 2013 second-round draft selection (35th overall) to draft Ertz out of Stanford, offensive coordinator Pat Shurmur said Celek is still the team's top tight end, because of his all-around versatility.
"Right now, you know, Brent Celek is our top tight end for a lot of reasons that I really admire," Shurmur said. "He's one of the toughest guys we've got. He fights, does everything we ask. And typically when the ball comes his way, he does a good job."
Celek's impact as a blocker has paid dividends for the league's top rushing attack, which averages 165.0 yards per game. For LeSean McCoy and Bryce Brown, having a run blocker on the outside such as Celek has allowed for increased running lanes for two non-traditional running backs.
"I thought he has been doing very well. He is blocking with a lot of effort, and that's really all you can ask for, and he has done a good job for us," Brown said. "I also think he is versatile. I think he can do a lot of things and he has really shown that to us consistently."
Even if he is a blocking threat, opponents cannot forget about the pass-catching threat Celek is, as well. With two touchdowns in seven games this season, Celek already doubled his total from last season when he played in 15 games.
"He catches the ball when it's thrown to him, and he has made some big plays for us over the years, and it's all about having opportunities," wide receiver Jason Avant said. "In this league, it's not always decline, it's not always a player's fault; it's about those calling the plays and being in the right situations or even the coverage. Your chances go up based on how the defense plays really."
When the Eagles played the Giants on Oct. 6, Celek caught a 25-yard pass from quarterback Nick Foles in the fourth quarter of the 36-21 victory. Hoping for a similar result, Celek said he might again be in the same position for a game-changing play.
"I can't talk about it, but it could be the same play. I don't know," Celek said. "Either way, we are going to have to play hard to earn a win, and they have a lot of big players, and hopefully, we can pull it out."
On Twitter: @JohnMurrow12