Cordero has plenty of velocity and occasionally hits 100 on the radar gun and stays consistently in the upper-90s. The problem has been in developing command of his fastball. In his minor league career, Cordero has walked 4.8 batters per nine innings of work, including walking 5.1 hitters per nine in his time with Double-A New Hampshire prior to the trade. The Phillies have stressed to Cordero that he has to focus on command and developing his slider. It's something that they've stressed with other power pitchers like Ken Giles and Nefi Ogando, with decent results.
"That's just like any of those guys that throw hard. We had [Luis] Garcia here, we had Giles here and there have been some guys who have thrown hard here. [Nefi] Ogando finally figured out that he had to pitch a little bit, too," explained Reading manager Dusty Wathan. He has to be able to command his fastball and his slider's a pitch that he's going to have to get better at, but you can say that about all of those hard-throwing guys; Giles was the same way, that's why he spent a little bit of time here, because his slider wasn't ready. Then, it was good enough to go to Triple-A and now, look at him."
When scouting Cordero against New Britain on August 9, he came on in the eighth inning and allowed one hit in the inning. All three of the outs that he recorded were on flyballs. His velocity was in the upper-90s, but he threw more sliders than he generally does, in an effort to develop that pitch.
Cordero started all four batters with a strike, three of which were on swings. In all, Cordero threw just ten pitches, six for strikes.
"Tonight, I thought he did a better job controlling himself and being effective in the strike zone," said Wathan after Cordero's August 9th appearance. "In the past, he was just trying to air it out and throw balls by guys and that works in A-ball a lot, but it doesn't work here on good hitters."