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5/9/2014 8:22 P.M. ET

Hart getting more comfortable at the plate

SEATTLE -- As a two-time All-Star and career .276 hitter, Corey Hart isn't proud of the .220 batting average he carried into Friday night's game for the Mariners.

But the 33-year-old designated hitter has come through in the clutch, hitting .304 (7-for-23) with 10 RBIs with runners in scoring position and his run-scoring single in the third inning Thursday was all the Mariners needed in a 1-0 victory over the Royals in the series opener at Safeco Field.

"He actually has been swinging the bat a lot better than the average has shown," manager Lloyd McClendon said. "He hit some balls pretty darn good on the road trip without anything to really show for it. It was nice to see him come through right there."

Hart has been getting more and more comfortable at the plate after missing all of last season with the Brewers following microfracture surgeries on both knees. He groans when his current average is mentioned, but does share the team lead with five home runs and is fifth with his 14 RBIs going into Friday's action.

"It's tough," he said of his first five weeks with the Mariners. "I'm kind of a notorious slow starter. This is kind of an odd season. I've missed some balls or hit a lot of hard balls right at guys. But it's getting a little more positive. I go to sleep easier. I'm not too far away from a good average and a lot of hits. I'll just keep working with the guys and hope the training staff keeps me on the field."

The Mariners need Hart's right-handed bat to produce as the cleanup hitter behind Robinson Cano and he averaged 33 doubles, 24 home runs and 78 RBIs over his last six seasons in Milwaukee.

"He's an important piece to what we're trying to accomplish," McClendon said. "This guy has a good track record. He's been off for over a year, but I would hope he can get back to being the player he was in Milwaukee because that was a pretty productive player.

"I see flashes of it and I still think it's going to take a little while, but I think he'll get there. I know from competing against him the past, when he gets hot, he gets hot. I see him real close to getting there."

Paxton feels strong in first bullpen session

SEATTLE -- Mariners southpaw James Paxton took the mound Friday and threw his first bullpen session since being sidelined just over a month ago with a strained lat muscle in his back.

Paxton threw 25 pitches and said everything felt great in his first time up on a mound since he went on the 15-day disabled list following his April 8 start in Anaheim. He'll throw his next bullpen session Sunday, moving up to 40 pitches as he works toward what likely will be a June return if all goes well.

The Mariners aren't setting any exact timeline, but Paxton and Taijuan Walker each will need a couple bullpen sessions, then likely a pair of simulated games before going out on Minor League rehab stints.

Walker will also throw a bullpen session Sunday, his first since being shut down with a recurring shoulder issue in mid-April.

"I really have no idea when I'll be back exactly," Paxton said. "But as long as I'm feeling good, it shouldn't be too far off. If I could decide, I'd be starting tomorrow. But I'm not allowed to do that."

For now, both youngsters will just follow trainer's orders, which means throwing in the Safeco Field bullpen for now.

"I felt awesome," Paxton said. "It was nice to get back up on the mound, that's for sure. It has been a little while, so it was exciting to get back up there and throw some pitches."

Paxton was limited to fastballs and changeups and didn't throw full out, as instructed.

"Right now I'm trying to get my timing back and just be smooth," he said. "They told me not to go full speed. Obviously it's not game-like right now, we're just trying to make sure it feels good and everything and it did. It was just nice and easy, smooth arm action."

Pitching coach Rick Waits said Sunday will be a big day with Paxton and Walker both taking the mound prior to that afternoon's series finale with the Royals.

"Taijuan looks great [playing catch so far]," Waits said. "He's just nice and loose and excited about getting on the mound, too."

Seager scratched with flu-like symptoms

SEATTLE -- Mariners third baseman Kyle Seager was scratched from Friday's lineup about 90 minutes before the first pitch against the Royals after coming down with flu-like symptoms.

Veteran utility man Willie Bloomquist replaced Seager at third base and took his sixth spot in the batting order as well.

Seager is the third Mariners player to deal with the flu bug in recent days, as catcher Mike Zunino dealt with the illness while in New York to start the last road trip and Felix Hernandez lost nine pounds and was under the weather in his start in Houston on May 2.

Seager was hitting .239 with five home runs and 19 RBIs in 33 games going into Friday's action.

Worth noting

• Right-hander Blake Beavan, who is on the 15-day disabled list with shoulder tendinitis, is rehabbing at the team's complex in Peoria, Ariz., and just began playing catch a few days ago, according to pitching coach Rick Waits.

• First baseman Justin Smoak led the Majors in two-out RBIs with 17 going into Friday's game. Smoak was tied for 11th in the American League with his 22 total RBIs in 34 games. Smoak had 50 RBIs in 131 games last year.

Greg Johns is a reporter for MLB.com. Follow him on Twitter @GregJohnsMLB as well as his Mariners Musings blog. This story was not subject to the approval of Major League Baseball or its clubs.