He knew that McGuire was already decorated, had been named the 2012 Dick Case player of the year by USA Baseball after playing on the national 18-and-under team that beat Canada to win gold at the IBAF 18U World Championship in Seoul, South Korea, last September.
He's well aware that McGuire is now viewed as a potential top 10 pick -- MLB.com has him going to the Mets at No. 11 in his latest mock Draft -- and hopes to follow Kentwood alumnus Matt Hague, who was a ninth-round pick in 2008, to the Major Leagues. Hague played in 30 games for the Pittburgh Pirates last season.
With all that in mind, Zender knew he and McGuire had to have a bit of a preseason chat about the very notion of expectations and reality and how far apart the two sometimes end up being.
"I talked to him about leadership and how that was his role," Zender said. "He'd always played up a level, but now he's a senior and all these kids are behind him. And he's been a really good leader. He's a fairly reserved kid naturally, but he stepped up and talked."
McGuire also had moments when he didn't have to talk, like during the first week of practice, when an assistant coach was in the school handling teaching duties and couldn't help oversee tryouts of ninth and 10th graders.
"I've got Reese with all these kids, so I said, 'OK, you know our regular routine for catchers, you take the catchers, you go through the drills and show them how to do it,'" Zender said.
"Some of these kids will never make [junior varsity] down the road, but he was down there working with them as if it was a private lesson. It was just fantastic."
It's not surprising given what McGuire has displayed.
On the field, McGuire is in the process of leading his team through the state tournament once again, and his 6-foot-1, 190-pound frame, his athleticism behind the plate, his emerging bat, and the fact that he's been clocked with a Major League-quality 1.77 "pop time" on throws from the plate to second base have the scouts ready to call his name earlier rather than later on June 6.
Off the field, even after all the publicity and chatter about how rich and famous he might soon become, he's the same Reese McGuire.
"All my buddies, are like, 'Oh, my gosh, dude, aren't you excited?', but I tell them this is all just the beginning," McGuire said. "They're saying, 'I better get your autograph,' and of course it's awesome, but I have to go out there and prove myself and work my way up just like everybody else."
McGuire is committed to the University of San Diego, but that could change in a hurry if the reality on Draft day matches the talk.
Reese's mother, Robin, teaches special education at Kentwood and watched as her eldest son, Cash, preferred to get a higher education while playing baseball. He took a scholarship and is an infielder at Seattle University.
"Reese's passion for playing baseball at the highest level is his ultimate goal, and if he's ready to go, we support him wholeheartedly," Robin said. "He really needs to sit down and think. He's already got a great offer on the table, so it's a full ride there or get started in the grind. It's exciting. We're definitely looking forward to it."
It's always been about baseball for Reese.
His parents built an indoor batting cage in their backyard, and Reese and Cash and their youngest brother, Shane, who will be on the Kentwood team next year, have honed their craft under its roof along with all their friends.
Reese grew up watching former Mariners backstop Dan Wilson and his favorite player, retired Red Sox catcher and captain Jason Varitek, and saw what it meant to be a steady presence behind the plate, for a club's pitching staff, and in the clubhouse.
"A catcher should be one of the No. 1 leaders on the field and on the team," he said. "I need to further develop my leadership skills and bring that role into the clubhouse. Also, offensively. I take just as much pride in that. I want to be an offensive producer as well."
The First-Year Player Draft will take place on June 6-8, beginning with the Draft preview show on MLB.com and MLB Network on Thursday, June 6, at 6 p.m. ET. Live Draft coverage from MLB Network's Studio 42 begins at 7 p.m., with the top 73 picks being streamed on MLB.com and broadcast on MLB Network. Rounds 3-10 will be streamed live on MLB.com on June 7, beginning with a preview show at 12:30 p.m., and Rounds 11-40 will be streamed live on MLB.com on June 8, starting at 1 p.m.
MLB.com's coverage includes Draft Central, the Top 100 Draft Prospects list and Draft Tracker, a live interactive application that includes a searchable database of Draft-eligible players. You can also keep up to date by following @MLBDraft on Twitter. And get into the Draft conversation by tagging your tweets with #mlbdraft.
On Draft day, McGuire said he'll be at home with his family. His grandparents will come over. There's a good chance he'll hear his name called early and the first part of his dream will come true.
He'll know that he'll have gotten where he is because of hard work and natural ability. He'll also know that he's only one rung closer to a goal that's still far away.
"Reese is just very down to earth," Robin said. "We've all kind of grown up that way. My husband and I are always about being grounded and making others better to better ourselves. Be proud of your abilities, but there's never any reason to hold yourself higher than anybody else.
"Reese is the same way."