How to assess Mike Moustakas’ first full big-league season after it ended prematurely Monday night when he aggravated a groin injury on a slide at second base in a 6-3 loss to Detroit at Kauffman Stadium?

It was a year in which he established himself as one of the game’s premier defensive third baseman, despite some final-week yips, while hitting more homers (20) and (through Monday) driving in more runs (73) than any Royal except Billy Butler.

His first words in self-appraisal: “It’s a disappointing year. Definitely disappointing.”

Moustakas, who recently turned 24, pointed first to the club’s performance before citing his own shortcomings or addressing the knee and groin injuries that affected his play over the final two months.

“First off, we didn’t make the playoffs,” he said, “which is the biggest disappointment that there can be. That’s why we play, to make the postseason and continue playing in October.

“And there are things I’m going to go back this offseason and work on, figure some things out and then come back ready to go.”

Pressed for specifics, and Moustakas agreed his power numbers are acceptable for his first full season but argues “my job is to drive in runs.” Then he pointed to a batting average (.242) that declined in the season’s closing weeks.

“My average is low and definitely not where I want it to be,” he said. “It’s something I’m going to work on. Getting the experience of this full year helps. Seeing these pitchers time after time, that helps.

“There are always things that need to be worked on. For me, it’s laying off pitches with two strikes. Maybe getting a little shorter, a little more compact, with my swing with two strikes. Things like that.”

Moustakas’ offensive decline coincided with a sprained right knee suffered July 29 at Seattle: He batted just .204 thereafter in 54 games with four homers and 23 RBIs — but he dismisses the connection.

“I don’t really think about things like that,” Moustakas said. “If I’m on the field, I’m 100 percent and ready to go. That’s not much of an excuse for me.”

The groin injury surfaced last Saturday in a 14-inning game at Cleveland and grew steadily worse over the next two days.

“I tweaked it or something coming in on a play,” he said. “I didn’t think anything about it. Then on the slide (Monday), I kind of tweaked it up again.”

Manager Ned Yost said Moustakas is “absolutely” a better player now than a year ago.

“In all phases of his game,” Yost said. “Look, if you’re looking for the finished product, he’s not there. He’s improved greatly all year long, defensively and offensively, but he’s still just scratching the surface of what he’s going to be.”

Moustakas is already anticipating a winter recharge.

“During the year,” he said, “you’re just grinding. You just concentrate on going out every day. Now I can take a step back and figure some stuff out.”

And then …

“When it’s all said and done,” Yost said, “I think he’s going to be a consistent .275 hitter with 25-30 homers and 100 RBIs and great defense.”

Hosmer done, too

First baseman Eric Hosmer is also finished for the year because of a strained right rotator cuff suffered last Thursday while diving for a grounder in Detroit. Until Tuesday, he and the Royals had not ruled out a return.

Revised plans call for Hosmer to return in roughly three weeks to Kansas City for a re-examination by Vincent Key, the club’s primary physician.

“He said he likes how it’s healing,” Hosmer said. “No surgery. I’ll come back in three weeks for another exam to make sure everything is good. He said it should put no delay on the offseason workouts.”

Hosmer finished the season at .232 with 14 homers and 60 RBIs in 152 games.

“Obviously, it’s not the way I wanted to go out,” he said, “but there’s no one to blame. I’ll just hold myself accountable for what happened, and I’ll use it as motivation to work as hard as I can and put together a good year next year.”

Throwing again

Former All-Star closer Joakim Soria took a notable step Tuesday in his recovery from a second Tommy John surgery to repair a torn elbow ligament by throwing a ball for the first time since exiting a March 18 game in spring training.

It wasn’t much: Just 25 tosses from 45 feet at the Royals’ year-round complex in Surprise, Ariz., — but it’s a start.

The Royals hold a club option for $8 million for next season on Soria but are expected to exercise a $750,000 buyout clause. The deadline for a decision is three days following the conclusion of the World Series.

Both sides have expressed interest in working out a new deal.

Soria missed the 2003 season after undergoing a previous Tommy John surgery while a member of the Dodgers’ organization. The Royals acquired Soria from San Diego in the Rule 5 Draft following the 2006 season.

Minor awards

The Royals placed two players on Baseball America’s list of the top 20 prospects in the Class A Midwest League: outfielder Jorge Bonifacio at No. 13, and right-handed pitcher Kyle Smith at No. 16.

Bonifacio, 19, battled a wrist injury in the closing weeks but still batted .282 with 10 homers and 61 RBIs in 105 games at Kane County. He was signed in December 2009 as a non-drafted free agent from the Dominican Republic.

“Jorge profiles as an everyday right fielder whose bat will carry him,” Baseball America reported. “There’s some violence and length to his swing, but he still controls the barrel well and could have plus power down the road.”

Bonifacio was the Cougars’ player of the year after winning that honor in 2011 at short-season Burlington and in 2010 for the Dominican Academy.

Smith, 20, was 4-3 with a 2.94 ERA in 13 starts at Kane County after winning his only start at short-season Idaho Falls. He struck out 98 and walked 21 in 721/3 innings for the two clubs.

The Royals picked Smith in the fourth round of the 2011 draft and pried him away from a scholarship at Florida with a $695,000 signing bonus.

“Smith is athletic, and his quick arm works well, generating fastballs that sit at 88-91 mph and top out at 93,” Baseball America reported. “His plus curveball is his best pitch, and he also has an average changeup.”

Instructs update

Outfielder Brett Eibner and third baseman Cheslor Cuthbert, players looking to rebound from disappointing seasons, each went three for four Monday in helping Surprise to a 12-8 victory at Goodyear in an advanced Instructional League game in Arizona.

Surprise is a combination team operated by the Royals and Rangers.

Eibner, 23, was a second-round pick in 2010 but batted just .196 this season in 120 games at Class A Wilmington, although he did have 15 homers and 53 RBIs.

Cuthbert, 19, entered the season ranked by Baseball America as the organization’s No. 5 prospect but batted .240 with seven homers and 59 RBIs in 124 games at Wilmington. He was signed in July 2009 as a non-drafted free agent from Nicaragua.

Gathright suspended

Former Royals outfielder Joey Gathright received a 50-game suspension from the commissioner’s office after testing positive for an amphetamine in violation of the Minor League Drug Prevention and Treatment Program.

Gathright, 31, is currently a free agent. He was released July 11 by Cincinnati following 40 games at Class AAA Louisville. He finished the summer by playing 68 games for Bridgeport in the Independent Atlantic League.

The suspension takes effect when Gathright signs with a major-league organization. He played for the Royals from 2006 to 2008.

Looking back

It was 19 years ago Wednesday — Oct. 3, 1993 — that George Brett concluded his major-league career by going one for four in a 4-1 victory at Texas. Brett got a single against Tom Henke in his final at-bat on a grounder that crawled up the middle.

Jeff Montgomery closed out the victory for his 45th save, which matched Dan Quisenberry’s club record. Montgomery and Quisenberry still share the club record.