Washington Nationals’ Sean Doolittle set to throw sim game today in Nationals Park...

Sean Doolittle acknowledged, after a brutal stretch which preceded a trip to the 10-Day Injured List, that his mechanics were out of whack after he attempted to pitch through some issues that he’d been dealing with, including right knee tendinitis.

“I don’t what came first,” the Nationals’ closer explained after he went on the IL. “I don’t if it was like a fatigue thing that caused the mechanical breakdown, or if the mechanical breakdown made me have to work a little bit harder and then I ended up getting fatigued. I don’t know. But at this point it’s just not right.”

The rough stretch saw the 32-year-old left-hander give up 13 hits, (five of them home runs), and 10 earned runs total (22.50 ERA), with a fairly brutal .520./.556/1.240 line against in his four innings on the mound in those outings.

GM Mike Rizzo told 106.7 the FAN in D.C.’s Sports Junkies last week that they were hard at work breaking down film and trying to identify changes to his mechanics that could help Doolittle straighten things out when he was ready to start throwing again.

“We watched a lot of film,” Rizzo said, “[Manager] Davey [Martinez], [Pitching Coach] Paul Menhart, and myself, to see if we saw any mechanical differences between Doo last year or early this year and recently, and we think we picked out a couple of things. Maybe because of the knee tendinitis he’s not exploding down the slope of the mound like he was early in the season, he’s not getting to his big balance athletic point where he can explode into the hitter which gives him that ride on the fastball and an extra mile or two on his velocity, so there’s different things that we think we’ve identified.”

“Doo is a very astute mechanical guy and really knows his body and mechanics,” Rizzo said.

“And he knows the art of pitching very, very well, and is one of the more intelligent athletes that I’ve been around in a long time, so we’re going to figure this thing out and get Doo back after this little hiatus I think of the IL. I think he’ll be refreshed and we can ride him into the last four or five weeks of the season and into the postseason.”

After three bullpen sessions, Doolittle told reporters on Tuesday that he was ready to take a step and throw a simulated game to test how he’s recovered while on the IL.

“I’m looking forward to tomorrow,” Doolittle said before the series opener with the Baltimore Orioles. “Getting some feedback from hitters standing in. We’re going to have some of the Edgertronic, the high speed cameras out there just so we can really break things down, and that’s kind of the final hurdle so we just want to make sure everything is where it’s supposed to be before we come back.”

“If it goes well we will see what happens this weekend,” his manager said, as quoted by MASN’s Byron Kerr, when asked about the closer potentially returning from the IL. “He’s actually doing a lot better. He feels good. So tomorrow we will determine what happens next. If everything goes well we’d love to get Doolittle back. But we’ll see how he throws tomorrow.”

Doolittle said the time off has helped him physically and mentally after the struggles were getting to him when he couldn’t figure out how to get right.

“I kind of needed a mental break,” he admitted.

“That two-week stretch there was really rough, and all through that process I was looking for answers, I was trying to find things and make adjustments and none of them were working, so when you’re spinning your wheels like that, it’s kind of — it’s a really helpless feeling. You’re searching for answers and you don’t really know how to fix it or where that fix is going to come from, so to be able to press pause and get my body right, it’s helped me a lot mentally as well, so I’m in a much better place right now.”

He did, he said, make some mechanical adjustments that he hopes will help to turn things around.

“We’ve changed some mechanical stuff that I feel really good about,” Doolittle said.

“The plan is to throw a simulated game tomorrow with the goal [of] being activated some time during the series against the Marlins.”

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As his manager said when Doolittle went on the Injured List, the plan is to bring him back as the closer when he’s ready to return, in spite of the struggles that led to the time off.

“I think this little IL stint helped him out in many ways, but just getting him right,” Martinez said.

“The biggest thing is getting him right and getting him to come back and feel good about himself.”

“Moving forward Doolittle will be our closer,” Martinez added, as quoted by MLB.com’s Jamal Collier.

“I said that before. This will be conversations that I’ll have with him; we’ll see where he’s at tomorrow and how he feels about everything tomorrow. I’m just waiting to see him pitch tomorrow and I hope that everything goes well, so we can have that conversation.”