Every Spring Training, prospects get a chance to show what they can do as they prepare for the season ahead. Some are competing for jobs in big league camp, others are prepping for the season as they vie for spots at Minor League affiliates up and down a team's system. MLBPipeline.com will be visiting all 30 camps this spring. Today, we check in on the Seattle Mariners.
PEORIA, Ariz. -- Over the past year, the Mariners have tried to instill a philosophy from the top down. The mantra is a simple one, one that isn't revolutionary or even outside the box in today's game. But for the Mainers to preach it from Seattle on down to the Dominican Summer League was something new.
Control the strike zone.
• Mariners' Top 30 Prospects list
Seems almost ridiculously simple, right? "It's simple, but it's not easy," Mariners farm director Andy McKay said.
The not easy part was getting everyone to buy in to the idea that better plate discipline will lead to both individual and team success, but the stats show the message has sunk in. Triple-A Tacoma was the only affiliate of the six affiliates in the United States to not improve in on-base percentage from 2015 to 2016, but even with that, the system as a whole improved by 112 points combined.
:: MLB Pipeline Spring Training reports ::
"We believe to manage the strike zone has direct correlation to winning games," McKay said. "In year one, when we were really taking a broad stroke organizationally, we won more games than anyone in baseball doing that. We were alive until Game 161 in the big leagues doing that. We put all [Minor League] teams in the playoffs doing that, but more importantly, from my perspective, it's really hard to find a player who wasn't better in 2016 than he was in 2015."
Team success and individual success can go a long way toward selling a philosophy. With all of those steps forward, McKay does get a different feel in his second Spring Training, beyond just a better familiarity with the facilities.
"We feel there's a lot more credibility," McKay said. "Whatever uneasiness that may have existed for our players, we kind of have the scoreboard in our favor now."
The winning percentage increase provides an added benefit. When players get to the big leagues, the expectation is one of winning. The Mariners have worked hard to change the culture in the Minors. Yes, each player should want to get to the big leagues, but by working toward a win, that will take care of itself, rather than just focusing on what individual performance is needed to earn a promotion.
"It's an easier game to play when your focus is 'how can I help my team win' rather than 'how can I get four hits so I can move up,'" McKay said. "The best way to be the best version of you is to focus on how you can be one of 25 guys trying to win this game tonight. That was the driver of the whole thing."
• Q&A with Dan Altavilla
Trades shape Spring Training competition
General manager Jerry Dipoto has certainly not been trigger-shy in making trades to improve the organization, with a focus not just on improving the big league roster, but also for filling in holes at the top of the farm system. As McKay said, "You'd need a wall of butcher paper to connect all the dots."
Take Dan Vogelbach, for instance. The first baseman, ranked No. 10 on the Mariners' Top 30 list, is in his first Spring Training with the M's, and has looked good so far. He came in July from the Cubs in the Mike Montgomery trade and he fits right into that new mantra with his career .391 OBP in the minors. But that trade netted more than just Vogelbach at first base.
"He is as advertised," McKay said about Vogelbach. "We gave up a very good player in that acquisition. You have Mike Montgomery, he threw the last pitch of the World Series. But you get Vogelbach and you get Paul Blackburn. Blackburn gets us Danny Valenica. You have Valencia and Vogelbach who could end up one heck of a platoon situation, for Montgomery. There are a lot of dots to connect there."

Vogelbach isn't the only new trade acquisition in Major League camp. Rob Whalen and Max Povse both came from the Braves in the Alex Jackson trade and both could impact the big league pitching staff in the relatively near future.
"From the minor league side, we traded a lot of lower level prospects, good players, for higher level prospects," McKay said. "Guys who are closer to helping us now. You identify players who would be good fits at your upper levels, who are closer to helping you in the big leagues. You find teams that might [have] a little abundance of those players. They have holes at the lower levels, we're trying to fill in the upper levels on our 40-man roster. You're not trying to win trades, you're trying to find partners."

Lewis continues to mend
Mariners 2016 first-round pick Kyle Lewis continues to work hard on his rehab as he tries to make his way back from a serious knee injury suffered during his pro debut. The raves about his makeup and personality continue to come in and he's not even playing anywhere, going through the long, often lonely, process in Peoria.
"He's as advertised," McKay said. "So much energy, that infectious smile. It's fun to be around. Wherever he goes, people like being around him. He makes things fun. In a perfect world, he'll be playing at a full-season affiliate by right after the All-Star Break, somewhere in there."

Breakout candidate
Joe DeCarlo has had difficulty getting his bat going since being drafted in the second round of the 2012 Draft. And he hit just .140 with a .521 OPS in April last year in the California League. That improved to .250 and .832 in May and he was productive the rest of the way, especially with a .322/.455/.556 August.
"From maybe May 15 on, he was as good as anyone," McKay said. "He's had some struggles, but he really put it together after a very difficult April."