Members of the Royals' front office had indicated since making the pick that they believed they would quickly reach an agreement with Zimmer, and that's just what they did.
"We're extremely proud to have him as part of our organization and extremely proud and happy that he was willing to get out here as quick as he did," said Royals assistant general manager J.J. Picollo. "It's a great day for us. We're anxious to get Kyle out and on the field as soon as we can."
Zimmer joins two other recent Kansas City top picks to sign on shortly after the Draft. In 2004, Billy Butler -- now the team's everyday designated hitter -- signed four days after being drafted. And in '10, Christian Colon -- currently playing middle infield with Double-A Northwest Arkansas -- signed by the end of June.
But quick transitions are nothing new to Zimmer, who was converted from a third baseman to a pitcher when he arrived at the University of San Francisco. His freshman year, there was not much of an opportunity for him to get playing time at third base. So coaches decided to turn him into a full-time pitcher, and the results speak for themselves.
"It was definitely a tough transition at first. It wasn't something that I immediately latched onto," Zimmer said. "I'd always been a hitter growing up. I just loved getting out on the field and playing the game. When my coaches told me that I was going to make that transition and they saw potential for me on the mound, I just sort of tried to take it as another challenge.
"It wasn't easy at first. There were definitely some hard, tough days I had to grind through, a lot of hours in the weight room and on the field trying to pick up things from some older guys and learn some new pitches. It was definitely a long process, but it was a fun one and I've grown to love pitching more than anything."
In a short time, Zimmer went from pitching just a handful of fill-in innings for his high school team to the first-round pick of a Major League team -- as a pitcher.
"I think it was a good decision," Zimmer said. "After I started getting the ball rolling pitching, it was just something that came naturally. I fell in love with it."
The Royals also were impressed.
"We as a scouting staff are looking for guys with good arm actions and deliveries constantly throughout the country," Royals scouting director Lonnie Goldberg said. "And to find somebody that jumped from a position player to get on the mound and be able to do what he's done -- and also command four pitches at the same time, a couple of them being plus pitches -- is very surprising."
Outside Butler and Colon, the trend for Royals' first-round selections had been to wait until the former Aug. 15 deadline. That was the case for Mike Moustakas (2007), Eric Hosmer ('08) and Bubba Starling ('11). In '06, Luke Hochevar also waited until early August. Alex Gordon and Aaron Crow -- the top picks of the Royals in '05 and '09, respectively -- didn't sign until September.
Picollo said that the new process of signing Draft picks is already showing positives, and he said it will allow more players to start playing professional baseball in the summer rather than waiting until the fall.
Zimmer will start his pro career right away. Picollo said he'd head to minicamp in Arizona in the next few days. General manager Dayton Moore said that Zimmer's "natural progression" could have him ending this season in the Midwest League and starting next season in the Carolina League.
According to Picollo and Moore, it will be a couple weeks before Zimmer sees any game action, as he is recovering from a groin injury. Zimmer explained the situation, but added that he feels in good health.
"It's a hamstring [injury] that sparked into a little bit of a groin [injury] when I was overcompensating. Hamstring is feeling great, groin is feeling pretty good, too, just a little bit of tightness. But my arm's never felt better," Zimmer said.
"We're going to get Kyle down to Arizona in the next few days," Picollo said. "He's got the little groin strain that we're going to address and get him healthy before he pitches in a game. We're going to see how that groin comes along, but it's probably going to be a couple weeks before we get him into a game situation."
The common phrase that popped up throughout the announcement and afterward was that Zimmer was just ready to start playing professional baseball, the main trait that was attributed to the quick signing.
"I didn't know exactly how it was going to play out," Zimmer said. "I knew that I was excited for this opportunity to get out there. I'm really looking forward to getting back on the field, being able to just feel the dirt under my feet again. It was exciting just to get out here and get this process rolling."
Vinnie Duber is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.