Pecota has Chapman at a .217/.311/.393 slash line, with plus defense, good for a 1.7 WAR (580 PA). Steamer is a bit more optimistic.
Regardless, I'm not sure that's the type of guy you commit to long term. I started getting some Mike Moustakas vibes and got the heeby jeebies. If When he ages off the position, the bat absolutely cannot handle 1B/DH. The back half of his upcoming contract figures to be an albatross, and really doesn't go very far toward upgrading the offense, if that is your intent.
Oh yeah...
Andy Ibanez .248/.305/.376 0.5 WAR (202 PA)
Zach McKinstry .222/.296/.361 0.2 WAR (361 PA)
Jace Jung .226/.309/.363 0.4 WAR (251 PA)
Colt Keith .241/.306/.387 0.6 WAR (294 PA)