Here's what I would say...
If all goes as planned, Sammy should be the #3 WR. He should be playing less snaps than both Bateman and Hollywood. If he's not, I think that's probably a knock on Bateman, or an injury happened.
The #3 WR in this offense is probably playing like 40-50% of offensive snaps, and maybe even less, if they're rotating somebody like Boykin as a run blocking WR. That could put Watkins down in the 30-40 snap range. If that's the case, I think durability issues could be lowered.
People need to realize... in KC, just last year, he was playing a TON of snaps. In the 10 games he played, he was over 70% like 8 times, and one of the games I believe he left early with injury. KC runs a LOT more 3 and 4 wide sets than the Ravens have. Maybe that changes, but I don't think it changes that much, given that Boyle will be back and we love two TE sets and utilize a FB as much as anybody.
So if Watkins is playing more than like 50-60% of the snaps, to me, it's either because he's playing over Bateman (which would be a knock on Bateman), somebody else is injured, or we're playing from behind a lot and need to throw. In pretty much all of those cases, it won't be by design mostly.