Marwin certainly. I really enjoyed Bregman's comments in a pre-game radio spot last week that he nobody knows more about playing defense in the major league's than Marwin and that he's pretty much attached himself to Marwin's hip since he came up and has learned more about how to play the game from him in that short time than nearly anyone else.
Springer seems more to me as the leader of the team, rather than just a "glue guy" which I see as more of a supporting role. Springer's the guy at the heart of Club Astros, every stylized celebration, and is a spokesman for the team.
I'd put Valbuena in a glue guy role too.
