Zimmer, Cole impress in Wilmington

I made my first trip to Frawley Stadium in Wilmington, Del., on Saturday night, receiving a wonderful welcome from the Blue Rocks' staff and catching a few famous pitching prospects in the process, thanks to a doubleheader against the Potomac Nationals.

Wilmington Game 1 starter, Kyle Zimmer, was the Royals' first overall pick in the 2012 rule 4 draft, a converted position player who showed a big fastball and curveball and had a very easy, athletic delivery that pointed to a top-of-the-rotation ceiling. All of that was on display on Saturday night, as he threw a seven-inning shutout. It was a game in which he gave up just two hits and one hard-hit ball while punching out six batters.

Zimmer showed three plus pitches on Saturday, led by a 93-97 mph fastball that he moved around the zone well and was willing to elevate to get swings and misses. He held that velocity into the final innings, still hitting 95-96 regularly as the game wound down. His curveball is still a thing of beauty, 78-83 with depth and angle to it, and he's comfortable throwing it to both sides of the plate.

The changeup was less consistent but flashed plus at 85-86, with some late action, but was more effective because he sells it so well out of his hand. The only below-average pitch he threw was his 85-87 mph slider, by far his worst offering with barely any tilt to it. However he used it far more often than was justified. Throw that out and you can easily project him as a starter who works with three pitches graded 60 or better if he just develops more feel for the changeup.

Of course, I'm burying the lede a little by omitting the fact that Zimmer had been terrible so far in 2013 before Saturday night, bringing a 5.92 ERA into the game while allowing eight homers in 65 innings, even though Wilmington is a pitchers' park where it's very difficult to homer. I can only speculate on why the guy I saw look so dominant on Saturday has given up so much solid contact, with a .341 BABIP before that outing, in high Class A. One possibility is overuse of the slider -- largely at the expense of the changeup, a pitch with more promise right now -- and that he needs to throw more to get more consistent with it.

A stronger theory is that Zimmer tends to rush through his delivery, which produces inconsistent results from pitch to pitch because he's not always releasing the ball at the same point. His tempo varies too wildly, and I think it starts because he drifts off the rubber too soon rather than staying tall and striding forward in a way that would let him control his body more. I haven't seen the “bad” Kyle Zimmer, so these are just my own hypotheses, but they're two things that could fairly easily be tested without much risk of harming Zimmer for the short or long term.

• The Potomac Nationals aren't exactly the '27 Yankees on offense, but they did roll out two legitimate prospect arms as starters in the two games on Saturday. A.J. Cole was the more impressive of the two, working at 93-97, mostly at the higher end of the range with very little effort and a very quick arm. Cole was originally drafted by the Nats, traded to Oakland in the Gio Gonzalez deal, then reacquired a year later in the Michael Morse trade after a disappointing year in the A's system.

Cole's main problem is that he's about a pitch and a half away from a starter's arsenal. In high school, he had a true curveball, but that's now become a slurvier breaking ball anywhere from 77-84, and he's getting on the side of the pitch, producing a flatter break and making it easier to see when he's throwing that rather than the fastball. (A Nats source told me that in Cole's previous outing, he was on top of the ball more and getting more depth, so I appear to have seen a lesser version.)

He barely uses his 80-82 mph changeup, and used it only versus lefties. He cuts off his delivery and comes across his body a little bit to get to his glove side, which isn't great for long-term shoulder health or for command. I loved Cole as a potential No. 2 starter after his huge 2011 season, but the Cole I saw on Saturday night is going to end up a reliever unless he gets that depth back on the breaking ball and develops a third pitch.

• Lefty Robbie Ray started the first game for Potomac, showing a four-pitch arsenal with nothing plus but some potential as either a fifth starter or a middle reliever. Ray's fastball sat 90-93 but played down because his delivery is all slow and his stride is so short. He gave up two homers to right-handed batters on the pitch, bringing his season totals to eight allowed to righties versus just one to a lefty. That's the result of the straight fastball and fringe-average changeup, which is behind the spike curveball that breaks sharply downward but is usually out of the zone. There's a little more in there than he's showing now, and speeding up the delivery or extending his stride might tap into it enough to make him a solid fourth or fifth starter in the majors at some point.

• There were no bats of note in either lineup, with Wilmington's Jorge Bonifacio on the DL and Cheslor Cuthbert recently promoted to Double-A. The Nats' lineup included Michael Taylor (not the former Phillies farmhand) who looks like he hasn't gained a pound since high school and was blown up by velocity all night. He needs to get a lot stronger before he can regain any sort of prospect status. Right now he's all looseness and athleticism but can't translate any of it into production.