Yeah. "Depth" is one of those words that is ill-defined. Every time someone says it, they mean something a little bit different.
In pure, clean terms, depth = number of bodies. If you have 9 or more guys who are suited up to fill thee three WR spots, you have very good depth.
But then, when some people say "depth," they mean "scholarship depth." They don't accept, and won't count, walk-ons. Only counts if we think enough of the kid that we're covering his tuitition. Paul Bain be damned.
And some people mean "experience" when they say "depth." As in, a freshman doesn't count for depth, because he hasn't yet bulked up in our S&C program, hasn't had a year to really get to know the system.
Then, some folks mash it all together and mean all of that. "Depth" for them is really "talented, experienced, game-changing 2nd and 3rd stringers."
For those last folks, very few teams ever have enough depth, at any position.
It's a very confusing word, considering how simple it starts out.