The Cincinnati Bengals drafted Eifert with their first-round pick earlier this year, while Gresham has been with the team since 2010.
The head coach told reporters: "In Jermaine, we felt like we got the total package, which is why we picked him when we did. When we were able to select Tyler where we selected, we felt like we were gaining a guy that already had incredible receiving skills that would grow into the physical part of playing tight end.
"He came in here and was better at that than I even expected. That's been the good thing. The game is not too big for him. He understands things. He does a great job of it.
"He's probably a little bit ahead of his time with the things that he's natural at. They've been a good complement to each other, and it's been great. In some ways, they both have learned things from each other."
The duo had five receptions each during the Bengals' opening game of the season.