Anyone can play SS, it just depends on what level of liability a club is willing to endure. There are plenty of shortstops today, who if re-evaluated by the same scouts as Guererro, would likely be told that they aren't a shortstop. I seriously doubt any scouts would say Asdrubal Cabrera or Jed Lowrie were shortstops if re-evaluated. You also have players like Hardy or Jhonny Peralta who appear too big, stiff and slow to play the position. I'd bet good money that if everything was equal, plenty of scouts would say those two are incapable of playing the position.