PITTSBURGH -- The Pittsburgh Steelers watched the Ladarius Green experiment fall apart in 2016 and didn't like the consistency of the Jesse James-Xavier Grimble-David Johnson battery in training camp.

They were "not consistently varsity enough," as coach Mike Tomlin classified it Tuesday.

The acquisition of former 49er Vance McDonald -- whom Tomlin calls an "NFL-caliber tight end" -- puts the team's current tight ends on notice, though that doesn't mean they can't all coexist.

"We're not going to anoint him in any way," Tomlin said of McDonald. "We're going to put him in uniform like the rest of them and continue to allow them to sort themselves out. It's reasonable to expect the guys that are here to respond positively in the right way to his presence and elevate their play."

It's clear McDonald can fight for a starting job once up to speed. With seven touchdown catches in the past two years, Ben Roethlisberger will likely utilize him in this area. Tomlin said he liked McDonald as a prospect out of Rice in 2013.

But he'll be jumping into a nuanced offensive system cold. Being ready for Week 1 beyond a few packages is a big ask. James and Grimble can still serve an important role in the passing game, particularly in the red zone.

Roethlisberger has gotten hundreds of reps with his tight ends over the past month, including many timing plays with James, who might not be the fantasy sleeper he was before the trade, but he'll still be a scoring threat.

Both James and Grimble had uneven training camps with several drops, but they also showed the ability to make athletic, splashy plays (see: Grimble's one-handed grab against the Colts).

It's possible McDonald and James will eventually split No. 1 reps, with Grimble used as a situational tight end and Johnson remaining as a key blocker.

That's if the Steelers keep all four on the 53-man roster, which is hardly a guarantee. But it is possible.