With a large contingent of teams looking to upgrade in center field and few answers to be found in free agency, the Diamondbacks are in an enviable position this winter. They don’t just have one starting-caliber center fielder. They arguably have four. And there may be no time like the present to strike a deal, not just to capitalize when the market is hot, but to potentially solve one of the team’s on-going needs at another position. Making a deal happen will be easier said than done, however, for a couple of reasons. First, the D-backs’ asking price figures to be quite high, given how few center fielders are available in free agency and the fact that general manager Mike…