Benteke was a 1 goal in 2 striker at Villa, 1 in 3 at Liverpool, and 1 in 5 at Palace. He's 30, so he's not getting any better, but I'd guess he's being brought in to start. Robinson's scored 5 goals in 32 games for West Brom, 3 of those in the half of those games that were in the Championship. He's just not the goal-scoring threat Benteke is. I'd have thought he'd be more likely to be playing off of Benteke than competing with him, but I don't know what West Brom's typical formation or their striker roster looks like.