A general manager’s work is never done — and it only gets more complex during the offseason.

One of the most complex issues facing the Twins is the infield.

Justin Morneau, of course, is set at first base. Beyond that — well, the combinations resemble a Rubik’s Cube, and one decision has ramifications for the others.

Consider, for example, Orlando Cabrera. He’s a free agent, and the Twins are contractually barred from offering arbitration — which means they’ll get no draft picks if he signs elsewhere.

The Twins like him — in no small part for things that don’t show up in the box scores. Ron Gardenhire apparently views him as a low-maintenance guy — just stick him in the lineup and let him play. (Ozzie Guillen did not have the same experience with Cabrera.)

And he was easily the best hitter of the six players who shared the bulk of playing time at second, third and shortstop.

But there are drawbacks to retaining Cabrera.

He turns 35 next month, and the former Gold Glover’s defense has slipped markedly the past couple of seasons. He was charged with 11 errors in two months with the Twins — and considering how lenient official scorers are these days, that’s saying something.

He played about a third of the season at short — 501 innings for Cabrera, 491 for Nick Punto, 451 for Brendan Harris — and made almost half the errors (11/7/6).

Errors are one thing; range is another. One reason Gardenhire went with Matt Tolbert at third base down the stretch was to cover ground in the hole that Cabrera couldn’t.

The notion here has been that prospect Danny Valencia would be the third baseman next season. Re-sign Cabrera, and that becomes doubtful; Gardenhire might opt for Tolbert’s glove over the promise of Valencia’s bat.

That’s a dubious choice, because the Twins clearly need better hitting out of the second-third-short positions. Of the 158 American League hitters with at least 225 plate appearances, Alexi Casilla was 158th, Tolbert 154th, Punto 151st, Harris 136th, Joe Crede 117th and Cabrera 115th in OPS. And that’s with Punto, Tolbert and Cabrera hot in the last month or so.

That’s just too many easy outs filling the lineup.

But Valencia, who spent the first half of 2009 in Double A and moved up to Triple A for the second half, lost control of the strike zone at the higher level. He drew 31 walks with New Britain in 57 games but just eight in 71 games with Rochester.

This probably contributed to the decision not to give him a September call-up. And at 25, he’s a bit old to be reckoned a budding star.