The nerves, Leyland said, are blocking him, which is why Leyland talked with Villarreal on Saturday morning and told him to just relax.
"Obviously, there's something going on where he's a little more relaxed [in Toledo]," Leyland said. "I talked to him today: Just relax, just do the same thing up here that you do down there. I mean, his equipment's plenty good enough, but for whatever reason up here, he's been a little erratic with his control."
Villarreal took the 7-6 loss against the Yankees on Friday night for a ninth inning in which he allowed the winning run to reach base and round the bases without the benefit of a hit, or even a ball in play. Back-to-back one-out walks, a wild pitch and a passed ball decided it.
Compare that to Villarreal's five games this April with the Mud Hens, holding opponents to two runs on four hits over nine innings with six walks and 13 strikeouts.
The fastball is the same 97-mph power pitch that impressed Leyland and coaches last year and this spring. Where it was going Friday was anyone's guess.
"The potential is there to be a very good Major League pitcher," Leyland said, "but in order to do that, he's going to have to harness that control a little bit. How long does it take? When will it come? Will it come? I can't answer that. But I think the ability to have a mental picture [of the game regardless of the surroundings] for him would be very good.
"It's no different up here. I mean, it is different up here, but as far as throwing the ball over the plate, at least you're giving yourself a chance. In last night's case, he just didn't give himself a chance."