Of course it's relevant.
If no-one supplies that kind of pass, goal-scoring opportunities are not created.
You have to remember that this statistic is compiled from ALL of Rovers' league-games. Downing may well have had a couple of games where he has been below his previous standard, but that doesn't mean he has been useless all along.
You seem to have bought into this idea that whoever Mowbray doesn't pick would be better than anyone he does choose. That is pure speculation. Putting out a team with Rankin-Costello, Buckley, Chapman, Butterworth in it might prove a magical solution; it might not. We don't know. And if you look at Barr's comments recently, he clearly doesn't think his players' recent performances have demanded promotion to the first team.