Jose Iglesias was taking batting practice the other day when he launched a home run that cleared a Green Monster-sized fence at one of the back fields of the Red Sox’ spring training complex. Standing in the outfield, resident wisecracker Dustin Pedroia hollered that he never knew Iglesias could hit a ball so far. “To the moon!” Iglesias yelled back. Coincidentally, that’s how far the Red Sox would go to find more than merely a stopgap for their revolving door at shortstop. Since Nomar Garciaparra was dealt at the trade deadline in 2004, 22 shortstops have started for the Sox, who somehow still have made five postseason appearances and won two World Series without a trace of stability at such an important position. Iglesias was supposed to be the answer. Signed to a four-year, $8.25 million contract after defecting from Cuba in 2009, he might be the majors’ best defensive shortstop if only he could remain in the majors. But he hasn’t hit enough at any level, including a hard-to-watch 8-for-68 stretch late last season that prompted the Red Sox to sign free agent shortstop Stephen Drew to a one-year contract and dangle Iglesias in trade talks. And so, Iglesias has arrived at a crossroads. At 23, he’s still too young to be cast off as a failure. But he also is no longer the Red Sox’ most touted shortstop, having ceded that distinction to 20-year-old top prospect Xander Bogaerts. There’s even more buzz surrounding Deven Marrero, the first-round pick who was surprisingly invited to big league camp despite being drafted only last year. “We have a lot of talented shortstops here,” Iglesias said before the Red Sox’ first full-squad workout yesterday. “But I can’t control that. My mentality is to be a better player every day, try to get better every single minute. That’s what I’ve been doing.”