Even if his throwing shoulder was nagging at him, Wade Miley had his mind set on pitching Saturday, knowing he’d be returning to Boston for the first time since the Red Sox traded him to Seattle in the offseason.

He was already looking at the numbers David Ortiz has been putting up this season, racking his brain trying to think of a way to keep the slugger from doing damage against him.

“That dude there, he’s special,’’ Miley said. “That’s a daggum career he’s had. What he’s doing this year is ridiculous. I’m looking, like, ‘How am I going to get this guy out?’ Do I just walk him? I’m lefty-lefty and I’m still not sure about it. He’s locked in right now.’’

But Miley’s left shoulder had been bothering him for the past two to three weeks, and it wasn’t getting better.

“It just kept barking,’’ he said. “It kept getting worse and worse rather than going away.’’

His outings weren’t getting any better either. In his last five starts, Miley was 2-1 but he had a 7.09 ERA.

He wanted to push through it, but the Mariners decided to place him on the disabled list Friday.

“He’s been struggling a little bit after his last start,’’ said Mariners manager Scott Servais. “Shoulder was bugging him a little bit . . . Thought it was best to shut him down and give him a chance to regroup. He’d only miss, if everything goes well, a couple starts.’’

Even though it meant missing a start he had been eyeing for a while, Miley acknowledged the decision was the right one.

“The way it was kind of progressing when it was starting, I wasn’t recovering like I wanted to,’’ Miley said. “I thought I would still be able to pitch Saturday, but then they felt maybe Sunday, maybe Monday. But like I said, the way it’s worked out, we need a little help right now. So they went ahead and did the DL.

“It’s just one of those things I’m just trying to be smart.’’

Miley, 29, had never been on the disabled list before in his career. Before the game Friday, he caught up with some of his old teammates.

“You always get a little extra adrenaline when you come back somewhere you’ve been before,’’ he said. “It would’ve been my first time doing that. But I was looking forward to it. “

Miley spent the first four years of his career in Arizona before being traded to the Red Sox in December 2014. The Diamondbacks weren’t on the Sox schedule last season, so he never crossed paths. This trip to Boston as the first time he’d return to old stomping grounds.

“It’s a little different,’’ Miley said. “It’s cool though. You get to see the guys. I seen some of the guys earlier. I loved my time here, it was awesome, but at the same time you get a little extra adrenaline, you want to come back and face these guys and you find out yesterday that it’s not going to happen. So it’s frustrating at the same time.’’

Miley was dealt to Seattle in December along with Jonathan Aro for Roenis Elias, who started Friday for the Sox, and reliever Carson Smith, who is on the disabled list after undergoing Tommy John surgery last month.

The trade came three days after the Sox signed David Price to a seven-year, $217 million contract. When Miley looked at the pieces the Sox were putting together between Price and lefthander Eduardo Rodriguez, he said he could see the writing on the wall.

“I mean, you kind of read between the lines a little bit,’’ Miley said. “When they signed Price, at the time there was three lefties. At Fenway, short porch, stacked righthanded lineup, you kind of go to thinking like, ‘There’s probably a good chance I’m the odd man out here with E-Rod and David coming in here.’ Not necessarily expecting it, but I wasn’t in total shock when it happened. You kind of understood the situation.’’

The Sox finished last in the AL East a year ago, and Miley with 11-11 with a 4.46 ERA, but he said he could tell by the way the Sox finished out the season that they could be as strong as they’ve been this year.

“We had a bad year last year,’’ Miley said. “We should’ve been so much better than what we were. We didn’t execute a things, but you saw the last two months of the season, those kids — [Travis] Shaw, Mookie [Betts], and Rodriguez — very talented team over there.’’

Miley said he didn’t expect to be out more than 10 days, and he’s already looking down the road to August when the Sox make a trip to Seattle for a four-game series.

“I wanted to pitch here, absolutely,’’ Miley said. “I was excited about it. Hopefully I get to catch them in August when we play in Seattle. It’s a little disappointing, but at the same time, trying to be smart.’’

Julian Benbow can be reached at jbenbow@globe.com. Follow him on Twitter @julianbenbow.