So, he's someone who doesn't throw a lot of strikes on the surface. Hollowell is a bit like Eli Morgan - he limits hard contact by generating lots of chase. They do it a bit differently, but it's a similar outcome.
When Hollowell is in the zone, you can get some swings on him; we saw that last night. Hollowell was clearly looking to throw strikes (he was in the zone more than normal). He's fastball-sweeper heavy - that sweeper needs to get off the plate and chase. He gave up EV's of 107 (xBA of .640), 99, 96 in his two innings Granted, these were against two players who likely end in Cooperstown (Freeman and Betts) and Edman (who's on a heater) so a little can be explained by that. But I think you get the idea; Hollowell in the zone probably isn't his home.
This are his total pitches thrown and his chase last night (pitches in the bold received swings) You'll, his o-zone pitches were generally "waste" pitches...no one is really going that far out of the zone to go get those. His sweeper sat in the zone a bit. His fastballs were mostly centercut.
If you can generate chase with Hollowell, if he can sit that sweeper on the outside against RHP there's a guy who can be used. His arm angle as Matt outlined in his article yesterday is funky, so deception is his friend. I don't think the Cubs have a back end guy, but if you told me he was Tyson Ross who threw a bit harder, I'd believe you.