SEATTLE -- One of the things lefty Patrick Sandoval wanted to improve this season was his ability to shake off miscues and minimize damage.

But it’s been in a work in progress much of this campaign, and that was certainly the case against the Mariners on Tuesday. Sandoval gave up three unearned runs after an error from third baseman Mike Moustakas in the first and four more runs in the fourth after another misplay from Moustakas in an 8-0 loss at T-Mobile Park.

Sandoval surrendered eight runs (five earned) on a season-high-tying 10 hits, and he leads the Majors having allowed 19 unearned runs in 26 starts this season. For comparison, no other MLB pitcher has given up more than 12 unearned runs. It’s indicative of the defense behind Sandoval, but also his propensity to allow things to spiral after something doesn’t go his way.

“I’ve got to get better at picking up the guys when things don’t go right,” Sandoval said. “To be the starter I want to be in this league, I need to definitely improve in that area. It’s just a constant letdown to myself. Whenever something goes wrong, I just can’t seem to pitch my way out of it.”

It’s something manager Phil Nevin has harped on all season with Sandoval, and he’s seen some incremental progress -- such as improved body language -- but now it’s about making better pitches to escape those jams.

“I've said it all along, the next pitch is too important,” Nevin said. “You've got to reel yourself back in, stay focused, make good pitches. He got hurt after those errors. He’s getting better at it. His body language is better. He’s attacking better after. And it’s understandable after things don’t go your way, but you have to make better pitches.”

Sandoval’s troubles started early when Julio Rodríguez reached on an error from Moustakas at third base with one out in the first inning. Teoscar Hernández followed with a slow roller to third, and Moustakas couldn’t quite make the play for an infield single.

Sandoval struck out Cal Raleigh for the second out, but then things unraveled. Eugenio Suárez and Ty France both connected on RBI singles before Dylan Moore doubled home another run. It could’ve been worse, but shortstop Zach Neto made a strong relay throw home on Moore's double to get France at the plate to end the inning.

It was a similar situation in the fourth, although Moustakas wasn’t charged with an error on a one-out grounder from France that got past him and was ruled a single. Moore and Sam Haggerty followed with singles to load the bases before Sandoval struck out José Caballero for the second out. But again, Sandoval had trouble getting the third out, surrendering a three-run double to J.P. Crawford that center fielder Brett Phillips nearly corralled in right-center field.

Moustakas, who left the game in the fifth inning with left wrist soreness and is day to day, shouldered the blame after the game for his play at third base.

“Those are three routine plays I need to make,” Moustakas said. “If I make any of those plays, Sandy has a great outing. It’s on me those plays weren’t made and he had to labor through some long innings and they scored a lot of runs because of it. And it’s on me.”

Sandoval went back out for the fifth but gave up a solo homer to Suárez with one out. He got through five innings on 92 pitches and the Angels were forced to use long reliever Jhonathan Diaz, who was a candidate to start Wednesday’s bullpen game.

Sandoval has posted a 4.48 ERA in 136 2/3 innings this season after registering a 2.91 ERA in 148 2/3 innings last year. Counting the unearned runs that have plagued him this season, Sandoval has allowed 5.73 runs per nine innings this season, which is something he knows he needs to improve on next year.

Right now, Sandoval said, it’s hard to find an easy solution because he feels like he’s making good pitches but isn't finding the results.

“It’s tough because I feel like I make really good pitches and then it’s sawed off and it lands behind our infield,” Sandoval said. “I feel like I make a good pitch, even if it’s outside the zone, and they swing at it and it drops. So I just have to keep working and keep grinding.”