Tribune-Review reporter Alan Robinson astutely points out Friday players who come off the preseason PUP list cannot be placed back on PUP for the regular season.
Barring any further injuries, Mendenhall will start the year on the roster, but the question is whether he'll be activated for the first game.
If he's not, the fact he's on the roster means there will be less running backs from which to choose.
Let's say Mendenhall doesn't dress for Pittsburgh's Week 1 game at Denver. Incidentally, the Steelers' depth at running back probably still be deeper than it was for their 29-23 overtime loss that ended their 2011 season. Without Mendenhall, who tore his ACL the previous week, RB Isaac Redman rushed for 121 yards in the loss, and he was backed up by John Clay. Mewelde Moore was out for that game, and Jonathan Dwyer had been placed on the IR. They signed RB Chad Spann from the practice squad and dressed him for that game.
Clay was the only other running back to get a carry in the loss.
The fact the Steelers chose to take him off the PUP is really more of a "put-up-or-shut-up" statement. They must feel, at worst, comfortable with Mendenhall taking a roster spot even if he may not be ready for the first few games.
It's likely the Steelers keep four running backs and one fullback. The second fullback would come in the form of a backup tight end, keeping three tight ends and five total running backs.
Judging the limited action so far, it would appear those four would be Mendenhall, Redman, Dwyer and Chris Rainey along with fullback Will Johnson (leaving practice squad eligible Baron Batch off the final roster).
It is possible - albeit unlikely - the Steelers use one of the tight ends in camp as their starting fullback, much like their plan was with David Johnson before a torn ACL ended his season. Johnson's ability to start at fullback and serve as the third tight end gave the Steelers the ability to keep five running backs and no pure fullbacks. They currently have veteran Justin Peelle, Leonard Pope, Jamie McCoy and rookie David Paulson battling for the third tight end spot with the 2TE spot open for the first games as Weslye Saunders serves a four-game suspension.
McCoy is said to be getting reps at fullback. He's played tight end primarily so far in his time in Steelers camp. Getting low is difficult when you stand at 6-foot-5 and taller, like the current Steelers' tight ends are.
They'll likely experiment a bit with that fullback role in Sunday's game against Indianapolis, but Mendenhall's return very well may have sealed the Week 1 roster. Whether Mendenhall will be able to play in that game remains to be seen.