But it's Detwiler's confidence in himself that's led to so much success over the last year. It was easy to see in his third straight strong start of the season, a seven-inning gem in which he struck out five and allowed only one run on a career-high 107 pitches -- 100 of them fastballs -- and led the Nationals to a 6-1 win over the Marlins at Marlins Park.
Detwiler now owns a 0.90 ERA, sixth lowest in the Majors, having allowed just two earned runs in 20 innings of work on the year.
"He's probably one of the best, obviously. If you look at his numbers, they're pretty good, which is an understatement," Marlins manager Mike Redmond said. "I like his approach. He just goes up there and pounds the zone with fastballs."
It's not accurate, of course, to say that Detwiler is only using his fastball, because he throws two of them: a sinking two-seamer and a four-seamer. But as usual, Detwiler relied almost exclusively on those pitches as he mowed through Miami's lineup.
He only threw seven offspeed pitches, all curveballs, and said he had to rely on his four-seam fastball more early on because he was overthrowing his sinker. But the Marlins simply couldn't get much going against the 27-year-old left-hander, who picked up his first win of the season.
"Well, yeah. 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.
It was another step in a process Johnson spoke about Tuesday afternoon, raving about how much Detwiler has matured, how much he's learned and how much he's still growing with each start. Detwiler proved his manager right Wednesday, showcasing what he's capable of -- filling up the strike zone with well-located fastballs -- and a hint of how he could be even more dangerous as he learns to more effectively mix in his offspeed stuff. If he needs those pitches at all, that is.
Detwiler has thrown 279 pitches so far this season. All but 31 have been sinkers or four-seam fastballs.
"He's a great guy to look at if you want to see that he uses his best pitch 85 percent of the time," third baseman Ryan Zimmerman said. "And the fastball, a well-located fastball, is still the hardest pitch to hit in the big leagues. I think some people forget that sometimes."
Detwiler got some help from a few other Nationals off to hot starts, namely Bryce Harper and Kurt Suzuki.
Harper, 4-for-5 with a double, continued his assault on Miami's Ricky Nolasco, with three of his four hits coming off the Miami righty, against whom he homered twice on Opening Day. And Suzuki, Washington's everyday catcher as long as Wilson Ramos is sidelined, raised his average to .360 with a homer, a triple and two RBIs.
The Nationals supported Detwiler with two runs in the second inning, the first on an RBI groundout by Roger Bernadina and the second on Suzuki's sacrifice fly to center. Suzuki then padded Washington's lead on his own in the fifth inning, working a full count against Nolasco before crushing his second homer of the season into the Washington bullpen in left field.
"Suzuki's been outstanding," Johnson said. "He did a heck of a job during the pennant race last year, and he's always working hard, handles the pitching staff great. He can get beat up and he still keeps coming. He's great."
The Marlins got a run back in the home half of the inning, albeit on a contested call. Chris Valaika knocked a leadoff double to center, and two outs later, Donovan Solano rapped a single to Jayson Werth in right field. Suzuki received Werth's throw at home and, based on the television replays, tagged Valaika's helmet before Valaika could get a hand on home plate.
Home-plate umpire Greg Gibson pulled his hand back, as if he was prepared to call Valaika out, but ruled that Valaika beat Suzuki's tag and scored Miami's first run. Suzuki, Detwiler and Johnson argued against the ruling, but the play stood as it was called.
"That was the question. I saw him go to ring him up and then he said safe," Suzuki said. "It was a little interesting, but it happens."
Not that it mattered. Harper led off the sixth inning with a double and scored on Adam LaRoche's single to left field. Suzuki wasn't done, either, leading off the seventh with a triple down the left-field line -- his first three-base hit since 2010 -- and scoring on a single by Steve Lombardozzi. Harper added an RBI with an infield single to plate Werth in the ninth.
That was more support than Detwiler needed on this night. The Nationals' fifth starter in name only finished up his seventh inning of work, walked into the Nationals' dugout and received a handshake from Johnson, having taken yet another step forward in his maturation as a pitcher.
"He's definitely not [a typical fifth starter]. He's got great stuff and he locates it well. He uses both sides of the plate as good as anybody I've seen," Johnson said. "He's still in the learning stages. But he's awfully good just right where he's at."