Marcus Semien has been something else this season.
Far different from the shortstop who previously struggled at the position and needed guidance from 10-year MLB infielder and former A's third base coach Ron Washington.
Now Semien finds himself quietly becoming one of the hottest hitters in baseball, but it's not going to be a muffled for long.
Entering play on Saturday, Semien is slashing .284/.365/.517 with 31 home runs and 88 RBI in 2019.
His improvement was spotlighted during a recent segment on MLB Network when Mark DeRosa and Bill Ripken gushed over how Semien's production has almost doubled in certain offensive categories.
Semien's 137 OPS+ is the tenth highest in the AL with his 7.4 WAR being the third highest in the league.
So what's working for him?
"He's controlling the strike zone, he knows what he's about," DeRosa said.
And Semien is being productive against a variety of pitchers at different fields as well.
His strikeouts are down quite a bit, and his walk percentage has risen along with his chase percentage -- that means he's increased his plate discipline, a factor DeRosa mentioned in regard to the maturation process a player has as seasons go by:
His slugging percentage against pitches 95-mph or faster has risen steadily as he's gone from .350 during the 2015-18 seasons to .625 in 2019.
Ripken and DeRosa tried to notice something different, but they agreed his swing was pretty spot on when comparing this season to last back-to-back.
[RELATED: Semien deserves MVP consideration]
Perhaps it was mental -- the confidence certainly shows. Perhaps the bat that he switched is a bigger factor than we realize.
But Ripken loves what he sees from a player who is playing every day.