I was at this Peoria game and walked away impressed with Rosario. The stadium gun wasn't working and I wasn't close enough to the players behind home plate so no exact readings. I saw Jokisch last year at 83-86 and Antigua in 2010 at 87-90, and Rosario threw noticeably faster than those two. Not as fast as Fabio Martinez-Mesa, though, who I also saw in 2010 at 95-96. I'm guessing Rosario's fastball sat between 90-93. He flashed a decent changeup with good deception and he didn't telegraph it with slower arm speed. He had some trouble commanding it, but when he did, he got a few swinging strikes. I only saw him throw the changeup to RHB though, which was weird. Rosario's best pitch was definitely his slider. It had tilt, depth and he threw it for strikes. He got several swinging and called strikes with it. In a bases loaded, two out situation, he struck out BA Vollmuth on three straight sliders, making him look bad. In the 5th and 6th innings, he started throwing with more effort and struggled with his command. It looks like I got to see Rosario on a good day, but even if his stamina continues to be a problem, I have no doubt he can end up being a high-leverage reliever, with a good slider and some extra oomph on the fastball in short stints. Other impressions: Zeke DeVoss is a really patient hitter. I didn't see him swing at one pitch outside the strike zone. Marco Hernandez wasn't very patient. He looked anxious and swung at a few pitches outside off the plate. When he did get a pitch in the middle though he hit a laser right back up the middle for a hit. He's really fast too. Turned a routine ground ball to 2B into a close play. On defense he didn't get a chance to show his range, but he definitely has the arm to stay at SS.