To start, Williams did publically single anyone out, as he didn't use any names. If a player has a doubt about whether or not Williams was referring to him, then I'd say that speaks for itself. If you even have to question yourself, you better pick up the tempo. So, this could have a positive effect on several plays, as opposed to a negative effect on one.
I would say that the player has to be either Shingo, Koch or Uribe .... with Schoeney as an outside possibility. I'll be very curious as to how he pitches today. He should be using all of his pitches by now, and pitching like it was April instead of March.