Summary
I talked a little about this with Javaris Reynolds, but the reason you like Culbreth is not what he's like right now as a pitcher. It's what he might become that got him drafted in the eighth round.
I wasn't able to see much video on him, but what I did seemed pretty positive. His delivery looks like it has a little bit of effort in it, but his arm slot is solid and doesn't have any glaring warning signs for future injury. I also only saw two pitches, so I really can't tell whether his delivery is repeatable or not.
But, with his leg kick and drive, I can tell why he was able to up his fastball velocity with some weight room work leading into his senior season. Before, Culbreth sat around 86, but with an offseason of work, he was reportedly hitting 95 this spring.
I'm sure his fastball will get better as he works out with the Astros, which is very positive. The only concern for me at this point is that he only has one secondary pitch right now. I'm sure he knows how to throw more, but I haven't seen any reports of other pitches. The Astros can certainly teach him those, but that also reflects how raw Culbreth is. He needs to get a feel for pitching as much as adding strength. That comes with time, and I'm confident he's got the frame and is interested on working hard to get better.
Floor
I guess, assuming he doesn't get hurt, that Culbreth's floor is as a reliever. As long as he adds a tick or two of velocity, he'll be able to be a somewhat effective reliever with just that pitch and his slurvy curve. But, as I said with Reynolds, the problem with projection is it might never come. There's as much of a chance that Culbreth turns into Ross Seaton or Jordan Lyles as Colton Pitkin.
Ceiling
I think Culbreth has the frame to be a workhorse starter. There's a lot that must click for him to get there, and I think we'll know more about his ceiling after he spends a year or two in rookie ball. But, with a fastball around 90-91 and two solid secondary pitches, he could fit into the back end of a rotation some day.
Will the Astros sign him?
Yes, yes he will (since he already signed).
Bibliography (Scouting Reports and video)
Below the jump
No video, unfortunately, though you can see a few short ones over at Perfect Game USA.
Culbreth has a good frame with broad shoulders at 6-foot-5, 200 pounds and generates solid velocity with his arm strength. He sits in the high 80s but could add more as he fills out. He has a slurvy breaking ball, but it has flashed sharp break at times. Inexperienced on the mound, Culbreth is a project but has the raw ingredients of an intriguing arm.