"He's got a little chip on his shoulder that he's trying to prove people wrong," said Angels bench coach Dino Ebel, who works with the outfielders. "That's the good thing about him. Like Albert [Pujols]. If you say he can't do something, he's going to prove you wrong. That's what Trout's mindset is -- 'I'm going to show everybody that I do have this arm strength, and I'm going to go out and do it.' And he has."
Trout did it on Friday night, when he fielded Jesus Guzman's single to center field and delivered a strong throw home to easily gun down Marc Krauss, giving him his first outfield assist since September 2012.
In the Spring Training that preceded Trout's historic rookie season, the Angels' 22-year-old center fielder was limited greatly by tendinitis in his right shoulder. And when he was optioned to Triple-A Salt Lake in March, he vowed to Ebel that he would improve his throwing.
Ebel believes Trout has "an average to above-average arm right now."
"He was on that fringe of average," Ebel said. "Now, he's past that. He's average to above-average -- when everything is right, his footwork."
Arm strength is probably the toughest aspect to improve because, as strength and conditioning specialist T.J. Harrington noted, the three muscles that account for how hard you throw -- the teres major, teres minor and infraspinatus -- are small and almost impossible to strengthen.
"Just look at bodybuilders," Harrington said. "You can bulk up and look great. It doesn't mean that you have functionality to do anything. You just look good. We'd rather have the joint strong, then put muscle on top of it. Now you can do whatever you want. But if you're bulking up on top of the muscle, you still don't have shoulder stability. You need that stability."
Resistance-band exercises, which Harrington has his position players do twice a week, helps strengthen those muscles, but there's no one exercise that can make you throw harder. The best way to improve arm strength, Harrington said, is through better mechanics and muscle memory, a byproduct of long-tossing.
Trout's arm was considered below average as he came up through the organization and even as he navigated through his first full season in 2012. But there was room for upside, because he entered the organization as a 17-year-old with raw throwing mechanics, and because he played in the Northeast, where harsh winters prevent players from throwing year-round.
Since his first full season, Ebel says Trout's arm is "way better."
"He's improving on it every day, he's working at it, and that's something he's taken pride in from Day 1," Ebel added. "He's doing the weight program, the shoulder exercises, we're throwing to bases more now, he's throwing more long-toss. He's showing an above-average arm now."