|Tsuyoshi Nishioka has generally appeared|
overmatched at the plate this season, and his
slash line of .208/.259/.233 agrees.
Alexi Casilla has 306.2 innings, Matt Tolbert 174 and Trevor Plouffe 133. Adds to to 969 innings, with Nishioka getting about 37 percent of the playing time, Casilla 32 percent, Tolbert 18 percent and Plouffe 14. (Rounding error means those figures add up to 101 percent.)
Offensively, Casilla is the only one who approaches acceptable. (His OPS — on base plus slugging — is .691, which ranks 62nd among the 83 American League players who qualify for the batting title and is roughly the same as Derek Jeter's and Torii Hunter's. Seven of the players behind him are are also middle infielders.) Plouffe has five homers, yes, but his batting average is below .200, his slugging percentage below .400.
Defensively, they all rate below average. The most recent set of the Baseball Info Systems metrics I have shows Nishi as -2 in plus-minus, -4 in runs saved; Casilla at -4 and -2; Tolbert at -1 and 0; and Plouffe at -5 and -4. (Those numbers are shortstop specific.)
Tolbert may not be the best defensive shortstop on the roster — clearly Ron Gardenhire doesn't believe so — but, for what it's worth, he also comes off best of six men who've played second base in those metrics. Nobody's been quite the blooming disaster at second that Plouffe was at short, but if Michael Cuddyer (-3, -3 in 115 innings) gets enough playing time there, that can change.
The Twins spent last offseason trying to find multi-year solutions to their middle infield. At this point, Nishioka has hardly established himself as part of the solution. The ever-inconsistent Casilla, maybe.
I am growing ever more curious about Brian Dozier, who opened the season at High A Fort Myers and hit .322/.423/.472 there, then moved up to Double A New Britain, where he is hitting .307/.374/.458. He turned 24 in May, so he's not particularly young for those levels (Plouffe is 25 and has tons of time in Triple A, a level Dozier hasn't touched yet).
Dozier may not be an answer. But I'm seeing increasing evidence that the players ahead of him aren't either.