ST. PETERSBURG -- Last week at Marlins Park, Ross Detwiler dominated Miami's lineup for seven innings. He gave up only one run, and even that was on a questionable call at home plate. Detwiler didn't walk anyone, struck out five and scattered seven hits.
And the Nationals left-hander did it all with his fastball -- almost exclusively with his fastball, in fact.
Detwiler threw 107 pitches in that April 17 outing, 100 of them fastballs. He threw only seven offspeed pitches, all curveballs. Detwiler was a fastball-heavy pitcher last year, throwing about 80 percent fastballs in 2012, according to the Pitch F/x data at BrooksBaseball.net. But he's taken it to a new level in his first four starts this season, throwing 379 fastballs in 420 pitches -- more than 90 percent.
"You've got to get guys out with your four-seam fastball in this league, or you're not going to last very long," Detwiler said in Miami. "But it goes to show you how you need to be able to locate your pitches. If you can do that, you'll get ground balls in key situations. ... I just try to focus on getting ahead in the count and keeping the ball down."
Those numbers and that philosophy have obviously pleased Detwiler's manager, Davey Johnson, who marvels at how effective his fifth starter has been since last season. Including his postseason debut in the 2012 National League Division Series, Detwiler owns a 2.88 ERA in 23 starts dating back to June 24, 2012. But it also brought a smile to the face of an opposing manager: Tampa Bay's Joe Maddon.
"I would love that guy," Maddon said, grinning.
Of course, anyone would love a 6-foot-5 left-hander who can touch 96 mph and who's given up only four earned runs in 26 innings to start this season. Nobody would complain about a fifth starter who ranks fifth in the Majors with a 1.38 ERA.
But that's not why Maddon smiled when he heard about Detwiler's fastball frenzy in Miami. It's because the Rays preach the importance of a fastball-first repertoire and fastball command as much as any organization in the Majors. It's how they've developed an incredible number of young pitchers, from the four homegrown starters in their current rotation -- David Price, Jeremy Hellickson, Matt Moore and Alex Cobb -- to the ones they've traded away, like Royals ace James Shields.
"Unless you can throw your fastball where you want it and when you want it, the other pitches almost become moot," Maddon said. "And if you choose to throw those other pitches all the time, you're probably going to get hurt."
But before we dig into the Rays' philosophy, one clarification about Detwiler: He's not just throwing one fastball. The lefty throws a powerful, sinking two-seamer and a straighter four-seam fastball. They both fall under the fastball classification, however, and Detwiler throws both with impressive velocity. According to the data, Detwiler is throwing his four-seamer at an average of 93.74 mph this year, and his sinker clocks in at an average of 92.53 mph.
"If you really think about it, it's two different pitches -- a four-seamer and a two-seamer," Nats catcher Kurt Suzuki said. "He throws to both sides of the plate, keeps the ball down, elevates it, throws 96 when he wants to. It makes it tough. I guess it goes to show you how important having a good fastball located, how effective it really is."
You certainly don't have to tell that to the Marlins. Detwiler threw 80 of his 107 pitches for strikes in that start and induced 16 whiffs.
"I like his approach. He just goes up there and pounds the zone with fastballs," Marlins manager Mike Redmond said. "He threw just a handful of breaking balls. But he moves that ball in and out. He has enough movement to keep guys off balance."
None of the Rays' young starters rely on their fastballs quite like Detwiler, of course. Even fellow Nationals starter Jordan Zimmermann is throwing a higher percentage of fastballs this season than any Tampa Bay starter. But according to Maddon's philosophy, it's no coincidence that Detwiler and Zimmermann have been Washington's most pitch-efficient starters this season.
With so many members of the Rays' staff featuring an arsenal of fastball, changeup and curveball, everything has to play off the heater. Tampa Bay has been averse to having its young pitchers throw cutters for a number of reasons, one of which is the organization's belief that it's nothing more than a bad fastball for most of them.
For the most part, breaking balls start off in the strike zone then end up as balls. Hypothetically, a disciplined hitter should have the sense to lay off those offerings and force the pitcher to throw strikes. That's why the Rays teach their pitchers to rely on their fastballs to quickly get ahead in the count and set up their offspeed pitches to get outs, whether it's by strikeout or by inducing weak contact.
"I believe the most successful pitchers that pitch a long period of time pitch with their fastball first, and then everything plays off of that," Maddon said. "I think the fastball pitchers with command and aggressiveness pitch deeper into games. That's why those are the guys that are in the seventh and eighth inning with decent pitch counts."
To a certain extent, that involves pitching to contact and letting the defense clean up ground balls and popups. Detwiler has only struck out 13 batters in 26 innings this season, for instance.
Nats third baseman Ryan Zimmerman, for one, said he has thoroughly enjoyed playing behind someone who fills up the strike zone with fastballs like Detwiler. It's a lot easier to line up behind a pitcher like that, Zimmerman said, than to line up against him in the batter's box.
"A well-located fastball is still the hardest pitch to hit in the big leagues," Zimmerman said. "I think some people forget that sometimes."
"Absolutely, no question. Totally agree with that. And that's how you get quick outs," Maddon added. "The group that goes away from that, it boggles my mind. They don't understand that concept."
Adam Berry is a reporter for MLB.com. Follow him on Twitter at @adamdberry.