Mason Thompson posted a 1.89 ERA, a 2.47 FIP, one walk, 17 strikeouts, and a .194/.217./313 line against in 11 games and 19 innings pitched in April. By the end of May, his ERA was up to 4.76, with a 4.00 FIP and a .252/.316/.383 line against in 21 games and 28 1⁄3 IP on the year, following a 10-game stretch in which he put up a 10.61 ERA, a 7.11 FIP, and a .350/.458/.500 line against in 9 1⁄3 IP.
Thompson, 25, bounced back with a strong month of June (in which he posted a 0.82 ERA, a 3.26 FIP, and a .189/.333/.216 line against in 12 games and 11 IP).
The difference month to month for the young(-ish) reliever?
“Just getting ahead, staying ahead, staying aggressive,” Thompson said, as quoted by Washington Post writer Andrew Golden. “That’s been the key for me from day one and got away from it a little bit there for a while. Just kind of lost that feel and just overall didn’t feel good about the way I was throwing the ball, how the ball was coming out of my hand. And over these last couple of weeks been feeling good, feeling like I’m back on track.”
Thompson’s short-arm delivery became a bit shorter, the WaPost reporter noted, and threw his mechanics off a bit when he was struggling which he and his coaches picked up after a rough outing in late April (which came two days after a three-inning appearance in relief, in which he gave up just one hit and struck out four of the nine batters he faced).
“What we are working on, for the most part, is the path of his arm,” [Nationals’] pitching coach Jim Hickey said in May during Thompson’s rough patch. “And it was great. I think we did him a little bit of a disservice when he pitched the three innings in New York and then asked him to come back with one day rest. I think that was probably the beginning of it. But it’s always something that’s been on our radar. This was something last year that we addressed. So it’s not like he’s just totally broken. He just needed a little bit of maintenance, a little bit of tinkering.”
The month of July was another rough one for the reliever, who put up a 9.00 ERA, a 4.13 FIP, and a .394/.462/.455 line against in nine games and eight innings pitched.
A few days into August, Thompson went on the IL with a left knee contusion.
“I don’t know how he fell, but he said he fell and he’s been dealing with it for a few days,” manager Davey Martinez told reporters, as quoted by MASN’s Mark Zuckerman.
“Hopefully it will go away. He had an MRI that showed he had a contusion. So we’re going to make sure we take care of him and get him ready to go again.”
His on-again, off-again struggles, MASN’s reporter noted, “... usually have coincided with an unwanted change to his mechanics, in which he starts short-arming pitches instead of reaching all the way back before delivering.”
“We talked about the shortness of his take-backs,” Thompson’s manager, Davey Martinez, noted before the reliever returned from the IL in mid-August.
“Getting him to consistently get his hand back there so everything’s fluid. We need to continue to work with that and make sure the consistency’s there with him.
“If he can do that, as we’ve all seen, he can roll out a quick two or three innings. We’ve seen him do it in less amount of time, because he’s got electric stuff.”
Thompson was back up a few days later.
“He was ready,” Martinez explained. “He was throwing the ball well. And it was his knee. It wasn’t like it was an arm injury.
“So we decided we needed a fresh arm, and Mason was the guy for us.”
In nine appearances and 6 2⁄3 IP between August 20th and September 10th, Thompson posted a 12.15 ERA, a 5.36 FIP, and a .441/.474/.706 line against before he was optioned down to Triple-A to make room on the roster for Jackson Rutledge to come up and start.
“He’s had some mechanical issues that we’re trying to work through,” Martinez explained. “I thought it was best just to kind of ease his mind a little bit. Give him less pressure, go down and work on some of the things we want him to work on. Mason is still a big part of our future. He really is. He’s had such a weird year. He was really, really good for a while and then not so good. We know what he can do when he’s really good. We’ve seen it, so we want to get him back there. For me, it was just about getting him down there, getting him to relax a little bit, working on some things that we want him to work on. I’m sure you’ll see Mason again.”