Grant Holmes will be a #2 Starter in the Majors someday. There's a slim chance his Changeup improves enough and he develops a 4th average to better pitch to make him an Ace and there's a fairly small chance that he can't refine his command enough to be more than a #3 Starter. There is no safer bet among the guys likely available at the 7th pick than Grant Holmes. Holmes is a Right Hander who stands 6'2" and weighs 190 lbs. His frame is filled out, so don't expect him to grow anymore. He has three pitches he throws regularly with good control: Fastball, Curveball and Changeup. Similar to Brady Aiken who I covered last, Holmes is capable of pinpoint command of the pitches and can get them over reliably for strikes. Also similar to Aiken, that ability to reliably get strikes with his secondary pitches was of some question before this season. His command has improved markedly and his Change was a warm-up pitch last year that he didn't use in games. He's relied on it in games this year and is confident enough to unleash it in key game situations.
We'll start by talking about his Fastball. He typically throws it 92-94, but can dial it up to 97 on occasion. The pitch has some arm side tail (in of Right handed hitters), but the movement is not significant. He also now shows an ability to work the ball to the glove side corner, something he didn't show in 2013. As I mentioned above Holmes isn't growing anymore so when he makes the Majors, he'll pretty much throw it 92-94, occasionally touching 97. He'll need to work to stay on top of the ball. As Baseball America notes here Holmes has a tendency to leave the ball up and his pitch flattens. That's fine against a lineup of guys destined for Intercollegiate Softball leagues and hitters not experienced enough to always recognize a meatball, but he can't do that often as a pro. So that's likely task one for him once drafted.
Holmes backs that pitch up with his Power Curveball. This is probably his best pitch at present. He throws it low-to-mid 80's and at least against High School kids the results look a little ridiculous at times. It's an out Pitch and has the potential to be plus-plus (it might be plus at present with his newfound pinpoint command of it). It could be one of the better out Pitches in the Majors when he eventually gets there.
His third pitch is his Changeup. It shows potential to be above-average. Currently there's about a 5-7 mph spread between his Fastball and Change. It's sometimes reasoned that the spread should be larger than that, maybe 8-10 mph, but that would make it the same as his hammer curve. This pitch already shows enough to be good without changing the speed further.
Could he add a Fourth pitch? It's possible as a pro he could work on a Cutter/2-seamer. I don't think a Slider would work, since his Curve is thrown at Slider speed, but I can't rule it out. Again, as with Aiken, I'm not going to analyze video this time, since there aren't many current videos to ascertain present strengths and weaknesses. I'll share a few I've watched though so you can see what he looks like and what his delivery is.
I think any team getting Holmes is likely to be happy with him, as a true #2 Starter is pretty damned valuable. I don't see the Phillies or anyone Top 10, likely, passing over the potential Aces available for him and he'll be long gone by Round 2. He'll last a while though in the round and I'd expect he'll be in the 10-20 range.
Here's a pretty current video courtesy of Perfect Game Baseball. I have to say he looks pretty stocky in his build and there's something old-timey about his very deliberate delivery.