"He was there for us from Day 1," Bosio said of Brockmeyer, 23. "I told him, 'I can't thank you enough.'"
Brockmeyer, who will open his season Thursday at Class A South Bend, was slated to arrive in Minor League camp in early March. But Minor League coordinator Tim Cossins asked if the catcher could come to Arizona early to help with the big league pitchers.
"I jumped at the opportunity," Brockmeyer said.
And who did Brockmeyer catch on his first day? Jon Lester, whom Brockmeyer had followed while growing up in Connecticut.
"They would always tell me, 'You'll be going back and forth,'" Brockmeyer said of his spring duties. "[Catching instructor Mike] Borzello would joke with me that I was on their secret missions or special ops missions. I was more than happy to jump in. Being there with the guys, it was a pretty life-changing experience."
The 6-foot-5, 235-pound Brockmeyer seems too big to be a catcher.
"He's a freak," Borzello said. "You're talking about a guy who's a monster, and somehow he becomes small when he's catching. You want to be a big target but catch small -- it's hard to explain. He can get underneath any baseball you throw, which makes it a lot easier to receive."
Has anyone ever told Brockmeyer he's too tall to catch?
"I've heard it a lot, that it was going to be a struggle, and I stuck with it," Brockmeyer said. "I loved being a part of the game and every play and getting dirty, so I stuck with it. People have given me a chance. I've learned and tried to use my body to stay flexible."
The key is yoga, which Brockmeyer does regularly, as well as plenty of stretching. He made quite an impression this spring.
"He has really long arms and is able to get down underneath the baseball better than anybody in camp," veteran catcher David Ross said. "We called him 'Octopus.'"
As a kid, Brockmeyer liked wearing the catcher's gear. He then went to California State University in Bakersfield and learned about the position from Mike Mayne, whose son Brent was a catcher for 15 seasons in the big leagues. Once Brockmeyer -- a 16th-round pick in the 2013 First-Year Player Draft -- signed with the Cubs, Cossins took him to the next step.
Brockmeyer earned the respect of Bosio and Cubs pitcher Jake Arrieta last year. Arrieta opened 2014 on the disabled list because of tightness in his right shoulder. While Arrieta was in extended spring camp, Brockmeyer was paired with the right-hander for his rehab outings.
"One of his first times, they brought me up to catch him," Brockmeyer said. "He did really well and I continued getting brought up to catch every one of his games. He went on to have a pretty decent year in The Show. It's funny, because Bosio now jokes with me that I was the one who got [Arrieta] on track.
"For me, personally, to catch these big leaguers, my job is easier, because they're throwing the pitches most of the time exactly where they want them to be."
Most of the focus among the Cubs' Minor League catchers is on 2014 first-round pick Kyle Schwarber, who will open the season with Double-A Tennessee on Thursday. Schwarber was in the Cubs' camp, but he received an official invite. Brockmeyer was a last-minute addition -- he kept his gear on the Minor League side of the complex, but joined the big league players for morning stretch and workouts.
"We joked about Brock, because he came to Spring Training because we knew he could catch, and wound up staying because he was so good and so impressive -- you didn't want to let him go," Borzello said.
Brockmeyer did all the early work with the catchers, helped with the bullpen sessions and side sessions, and sat in on discussions about the position. It was a big leap for the catcher, who spent last season at Class A Kane County.
This spring was one Brockmeyer won't forget, and now he takes those lessons to South Bend.
"It helps you keep working and building off what you're doing, and lets you know, 'Hey, I'm doing something right now,' so I'll keep heading in the right direction," Brockmeyer said. "Hopefully good things will happen."