"He and my mom know my mechanics better than anybody," McCarthy said. "If he sees something that stands out, he'll let me know."
Or he'll pass along the standard reminder that he has been passing along since the two started playing catch in their back yard 20 years ago.
"Bend your front knee!"
Said McCarthy, "I think I've outgrown that, but he swears by it."
Patrick McCarthy is a professional fundraiser for non-profit organizations, but he has always been the biggest influence on Brandon's professional baseball career. That's something Brandon has never forgotten and the two were planning to be together on Father's Day this weekend with the Rangers in Cincinnati to play the Reds.
They have been together in this journey toward baseball excellence from Wiffle ball games in the back yard when he was two years old, up to his Major League debut with the Chicago White Sox at Wrigley Field on May 22, 2005, and beyond.
"I remember my big-league debut and how proud he was," McCarthy said. "We were playing the Cubs at Wrigley and they flew in the night before. Their luggage got lost and that was a hassle. Everybody was stressed out and trying to relax. I was pitching against Mark Prior and he was one of my heroes. I gave up a home run to Henry Blanco, but I pitched 5 1/3 innings and left with the lead."
The Cubs rallied to win, but it was still a memorable day, the ultimate dream of Patrick and Brandon McCarthy.
"I remember when I was two years old, running around the backyard in diapers and my dad pitching to me with a Wiffle ball," McCarthy said. "Growing up, we would play catch in the back yard or he would pitch to me, until I started hitting it over the fence and into parking lot of the neighborhood parking lot. That put a stop to that.
"I would be all my favorite Dodgers. Orel Hershiser was my favorite pitcher and for some reason, I was a big Steve Sax fan. I knew who all the base coaches were, everybody."
He also knew who his pitching coach was.
"He always knew a lot of mechanical stuff and worked with me on it," McCarthy said. "He had a good feel for it. I remember in Little League he was calling pitches for me and the other coach made him stop. I was just learning to throw offspeed stuff and learning the proper sequences."
Patrick also taught Brandon a trick or two. Well, at least one.
"He did teach me a knuckleball," McCarthy said. "I had a good one, but that kind of went out when I went into pro ball."
McCarthy now comes at hitters with a fastball, curve, slider and a changeup, a big-league repertoire with a big future made possible by a dad who knew pitching and was there every step of the way.