I call BS on this. Some hitters have the skill of shortening their swing and going for a hit that drives in a run. I think Westburg has that. After watching a season of some O's hitters swinging from their heels to hit fly ball outs to the outfield it would be refreshing to add a player that actually knows how to work a count, hit a line drive and drive in a run.
I agree with your 2nd point though none of the four guys you mention were at the same club as Westburg all season long. And getting 106 RBI is an all season long effort.
Here is a thought.
Maybe Elias values Bemboom defense and mentoring capabilities. Maybe he wants Bemboom to mentor Handley at AAA. Bemboom was about to become a minor league free agent and Elias wanted to show him how much he is valued. So he puts him on the majors league roster while other catchers are scrambling for roster spots. At some point Elias will DFA him and sign him to a minor league contract.
Both Nottingham and Cumberland are known for their offense not defense. But maybe its not offense that Elias is looking for in a mentor for Handley at AAA.
One of the things on Elias' list to do this off season is build a AAA team. And consider that Elias has used 60 players in the majors each season. Maybe early next season Elias sees Bemboom as his third catcher that will be at AAA while Handley is still in development. Because of Bemboom's defense not his offense.