Pella's been shit lately, don't know how Greul's been playing well lately either.
Pella has been OK of late. Maybe he's getting a bit tired with the long season but his results aren't that bad.
Greul is a good player that consistently does well in challengers and he's a veteran. He knows what it takes to win. Plus he's a good counterpuncher. An attacking player like Pella will have trouble with that.