The 28-year-old right-hander averaged 93.7 mph with his fastball in 2014 and averaged 93.5 mph with the heater over the course of his career, but he was sitting around 92.1 mph over the first month-plus of the 2015 campaign.
"Don't really care about velocity, as long as I make my pitch," Zimmermann told reporters.
"You can throw 85 and make your pitch and get guys out up here as long as you execute and mix it up and I'm sure it will come back later in the season but just down a little bit right now."
It appears to have come back sooner than later for the '07 Nats' second-round draft pick. In Petco Park last night, in the second game of the Nationals' four-game set with the San Diego Padres, Zimmermann's fastball averaged 94.4 mph according to Brooksbaseball.net and maxed out at 95.8 mph, up a tick from his season average of 92.4 mph on his four-seamer.
Zimmermann had everything working last night over six scoreless innings against the Padres, and was only really in trouble once when San Diego loaded the bases with no one out on three straight singles in the bottom of the fifth.
He went right after the next three batters, however, striking out Jedd Gyroko, popping up Cory Spangenberg and getting a weak grounder to first out of Abraham Almonter to leave'em loaded and keep the home team off the board through five.
A quick, 14-pitch sixth ended his outing and after the game he explained what has been different for him over the last few outings after he struggled out of the gate this season.
"'I was just a little out of whack mechanically and flying open,'" Zimmermann told reporters, including the Washington Post's James Wagner in discussing the issue in his earlier outings.
"'The last couple starts have been a lot better and staying on the ball,'" he said. "'The velocity is there now and the fastball command is right where I want it.'"
Zimmermann, for whatever reason, has always pitched well in San Diego.
After last night's outing, the Auburndale, Wisconsin-born starter, who is headed for free agency after this season unless he and the Nationals agree on a long-term deal between now and this winter, is now (3-1) in five starts in Petco Park with a 0.50 ERA, two walks (0.50 BB/9) and 40 Ks (10.00 K/9) in 36 IP over which he's held Padres' hitters to a combined .181/.206/.252 line.
"He's pitched really well here," Nats' skipper Matt Williams said after the Nationals' 10-0 win.
"They had three guys in the lineup tonight that have had success against him, the two guys in the middle [Matt Kemp and Justin Upton] and [Clint] Barmes had success. But he feels comfortable here. He pitched, again, well. We got him out of there earlier this time than last, last time it was pretty stressful for him, so at 90 we decided to get him out of there and get A.J. [Cole] in there to save the bullpen a little bit, and get Jordan out and let him get to his next start as well."
Zimmermann was successful, Williams said, because he was able to command the ball down in the zone consistently.
"He was down in the zone more, ball was down," Williams explained. "He missed a lot down as opposed to missing up. He was able to climb the ladder late with the heater too, so as he got into the fifth and sixth inning he started throwing breaking balls for strikes early as well. Good job."
"He's got a good arm, as you guys know," Padres' skipper Bud Black said.
"I mean, he's had a couple good years now of pretty good production. Sneaky fastball that stays true with velocity. It doesn't lose any steam. Even though it's 91-92-93, but it carries through the zone and he just beats bats with a low-90s heater and a good tight little slider. Not many changeups.
"It's the fastball/slider combo with excellent life to the fastball, as good life to the fastball as anyone in the game when he's right and he was on tonight. He had nice hop in the zone and we just couldn't square the ball up."
With his six scoreless innings of work, Zimmermann lowered his ERA on the year to 3.66 after 46 ⅔ to go along with his 3.19 FIP, 30 Ks (5.79), after he added six, and 10 walks (1.93 BB/9), after he issued just one free pass.
He also extended his unbeaten streak to five straight starts after he lost two in a row in his second and third outings of the year.
Over the course of that unbeaten streak, Zimmermann has a 2.45 ERA in 32 IP, with a .276/.305/.317 line against, and though he's just (2-0) in those outings, the Nationals are 4-1 in his last five starts.
The Nats received some bad news on Thursday night, when they learned that right-hander Doug Fister was experiencing tightness in his right forearm, but on Friday they got some good news.
Jordan Zimmermann appears to be back.