Now the two are navigating through a critical juncture of their relationship: the trust portion.
See, Trumbo is someone whom many would describe as a tireless worker -- "a perfectionist," as Picciolo calls him. That's good. But sometimes that mentality can have a negative effect on Trumbo's development at third base, because he tends to be a little too hard on himself whenever he misplays a ball at a position where he isn't awfully comfortable in the first place.
Trumbo committed a team-high four errors at third base in Spring Training and has already compiled three in two starts there during the regular season -- on an errant throw to first base, a bobbled grounder and a missed foul popup.
He takes every one of them to heart.
"I take it very hard," said Trumbo. "I know how hard the pitchers work to get those outs. They work hard to get the ground ball, and if you can't complete the play behind him, you feel terrible. But I also have to let it go as quick as possible, because another one may be coming my way."
That's what Trumbo and the Angels' sports psychologist, Dr. Ken Ravizza, are working on. Since Trumbo's rookie season last year, the two have talked twice a week about building confidence, eliminating negative vocabulary, breathing properly and, as Trumbo described it, "Coming up with some routines to help you when the pressure really sets in."
Trumbo used those tools to his benefit at the plate in 2011, when he led the Angels in homers (29) and slugging percentage (.477).
In 2012, the former first baseman is looking to do the same -- on the other side of the field, and on a new side of the diamond.
"I think one of the skills [in baseball] is letting go of the last play, last pitch, and getting to the next pitch," said Ravizza, who didn't want to go into specifics about what he and Trumbo discuss.
"That's not easy. It's a skill. I think Mark really learned that skill last year at the plate, and now he's going to use that same approach [on the field]."
That's the Angels' hope, because right now, manager Mike Scioscia is still getting a feel for how much time Trumbo will get at the hot corner compared with the better-fielding-but-weaker-hitting Alberto Callaspo.
All will hinge on how well Trumbo continues to progress at the position -- one where he has also turned in a few highlight-reel plays on line drives -- and also how well his bat plays.
Ultimately, though, it'll hinge on how he is able to flip that switch when things don't go his way.
"I wish I can let [the errors] go a little bit easier, but it's probably because I have that pitching background," said Trumbo, who doubled as a hard-throwing right-hander in high school. "As a pitcher, I remember how hard I used to work to get a ground ball. You get a little excited when you do. And next thing you know, it's like, now we have another situation in hand."
Trumbo was officially told he'd be moving from first to third shortly after the Angels signed Albert Pujols on Dec. 8, but the stress fracture in his foot delayed the start of that process until early February.
Slowly but surely, Trumbo and his oversize infield glove progressed from fielding grounders on two knees to standing up to field balls hit directly at him to finally getting medically cleared for full baseball activities on Feb. 29.
Suspecting he'd try to abuse that freedom, the Angels made sure they monitored Trumbo's workload early. So this spring, while Picciolo hit grounders and first-base coach Alfredo Griffin dictated instructions, one of the trainers would stand by with a clicker -- the same one coaches use to track pitch counts -- to make sure Trumbo didn't field more than 40 or so grounders each day.
"He never says he's had enough," Picciolo said. "You always have to put the reins on him and say, 'That's it for you.'"
But Trumbo wants to keep working, because it's so important for him to consistently make the routine plays.
See, Trumbo and third base need each other.
Third base needs Trumbo to play it well so Scioscia has a means to get his bat in the lineup -- a bat that will make the Angels' offense a lot deeper and provide some needed protection for Pujols.
And Trumbo needs third base because, well, it's really all he has. With Pujols now at first, a recovered Kendrys Morales entrenched at designated hitter and the outfield essentially set, it's really his only hope of getting consistent playing time on this team.
For that to happen, the two need to trust each other. And that's why Trumbo won't watch videos of any of his errors at third base.
He only wants to recall the good times.
"Going into a game remembering the blunders I've had would just bring things down more," he said. "So my whole thing is to just go in there with as much confidence as I can, replay some of the good things I've done and try and have those as the last memories I have going into a competition."