DETROIT -- Though the Tigers' second-half opener, a split doubleheader with the Twins, was rained out, Detroit continued to strike the balance between giving young players a chance and creating competition for spots based on performance. While infielder Willi Castro was optioned to Triple-A Toledo, veteran outfielder Nomar Mazara was designated for assignment.

Neither Castro nor Mazara has performed anywhere near what the team hoped going into the season. Both will make way for young players to get a chance, with infielder Isaac Paredes and outfielder Derek Hill recalled from Toledo.

The demotion is a blow for the 24-year-old Castro, who finished fourth in AL Rookie of the Year voting last year coming off a stellar six-week stint as the Tigers’ primary shortstop. He still has a chance to be a part of Detroit's future core, but the team’s patience ran out waiting for him to dig out from a slow start.

“We’ve got to get Willi back on track,” manager A.J. Hinch said. “Our best team has him involved and has him playing virtually every day.”

The Tigers went into the season fully aware that Castro’s primary value was his offense. Even after determining a month into the season that Castro wasn’t the long-term answer at shortstop, Detroit stuck with him as the primary second baseman. But the long-anticipated offensive turnaround never happened, and by midseason, the offense and defense arguably dragged each other down.

Castro’s .619 OPS is 313 points below his mark from last season. His OPS+, a measure of where his OPS stands compared to others at his position, dropped from 154 last year to 73 this season. His .214 average (54-for-252) includes 10 doubles and six homers to go with 28 RBIs.

The metrics show Castro’s struggles across the board. His batting average is down compared to last season against all kinds of pitching, according to Statcast, including a .212 average against fastballs. Despite a higher strikeout total, his swing-and-miss rate and average exit velocity are similar to last season, but his hard-hit rate dropped to 26.5 percent -- among the bottom three percent of Major League hitters.

Those struggles left Castro batting in the bottom third of the Tigers lineup for the past month. Meanwhile, the defensive metrics that had team officials concerned about his positional fit worsened this year. His minus-7 Outs Above Average, including a minus-6 rating at second base, placed him among the bottom two percent of Major Leaguers.

The Tigers aren’t giving up on second base as a position for him yet. He’ll focus his efforts there in Toledo.

“I do think we’ve seen some progress defensively,” Hinch said of Castro. “Overall, the defensive metrics aren’t very kind to him, but we’ve seen progress at second base and we want to continue to see that. But a lot of it has to do with getting his bat on track. He had such a good breakout season last year in the shortened season and really just hasn’t been able to get on track consistently. He even admitted that to me in my office, that he’s just struggled too long.”

The move might have happened sooner if not for Paredes’ own struggles. The 22-year-old hit just 5-for-29 and grounded into four double plays over two brief Tiger stints this year, though his six walks and two sacrifice flies are a reminder of the plate discipline that earned him an opportunity last summer. He’ll get a look at second and third base, with Jonathan Schoop alternating between first and second and Jeimer Candelario bouncing between the infield corners.

“People are going to fight for playing time, and that’s a good thing,” Hinch said.

Mazara isn’t much older at 26, but his exit had been anticipated amid a second consecutive season with a sub-.600 OPS. The Tigers signed him just before Spring Training as a free agent in hopes of helping him back to his productive form from his Texas days, but he batted .212/.276/.321 with five doubles, three home runs, 19 RBIs and 45 strikeouts over 165 at-bats.

Injuries to Hill and Daz Cameron extended Mazara’s stay. But with Hill back up to speed following his right shoulder injury last month, the Tigers want to give him an extended look in center field.

“I really want him back in the big leagues,” Hinch said. “Derek’s defense is really second to none in our organization in the outfield, so I think that will bring a ton of energy out there, a ton of productivity. The stuff he was doing on the bases before he got hurt was very appealing to me and the rest of the coaching staff.”

By designating Mazara, the Tigers will eat the remainder of his $1.75 million contract. As a player with five-plus years of Major League service time, he can decline an outright assignment to the Minor Leagues if he clears waivers.