That sounds like a lot, but it really isn't.
It's not that unusual for teams to have a lot of shortstops on such lists, because most amateur position players who get pro contracts were shortstops in amateur ball. A player with the physical gifts to someday play major league baseball is probably the best athlete on his high school or college team, so they play short. A lot of them get sorted out to other positions early, of course, but the best talents open at shortstop and play their way off the position.
This list of five is quite heavy with players at the low levels of the system.
Javier, who was signed out of the Dominican last summer as a 16-year-old (breaking Miguel Sano's record for the biggest bonus the Twins have given a Dominican) hasn't played an inning yet. Presumably he'll start in the Dominican Summer League this year; if he dominates there, he might emigrate to the complex team in the Gulf Coast League. We are years from Javier making an sort of impact.
Palacios started 2015 at the GCL and moved up to Elizabethton in the Appy League. He hit well, but that doesn't mean a whole lot, especially in E-Town. My guess is that if Palacios makes it to the majors, it will be at another position, but that's purely a guess. He's all of 19, so there's plenty of time.
Gordon had a fine season at Cedar Rapids, and figures to open 2016 at Fort Myers in the Florida State League. That's still A ball, still a step south of the levels of the farm system from which a player might reasonably get the call to the majors. We're still a year or two (or more) from the 2014 first round pick challenging Eduardo Escobar for the big league job.
Vielma was the shortstop at Fort Myers. People rave about his glovework. From the BA writeup:
... the organization's best defensive infielder ... Vielma has soft hands, smoth actions and outstanding footwork to go with a plus arm and jaw-dropping range.
The question is: Can he hit? He's apparently a bit bigger than he was when I saw him sitting out with an injury in Cedar Rapids in 2014, and his numbers didn't take a noticeable hit when he moved from the hitter-friendly environment of CR to the pitcher-friendly FSL, and those are both encouraging facts. On the other hand, he doesn't have much strike-zone discipline. He'll go as far as his bat can take him.
And that leaves Jorge Polanco, who is more likely a second baseman. I'm slightly surprised he's still in the organization; management seems committed to Brian Dozier at second base and Polanco is an ill fit at short. It's quite possible that he will be an in-season trade chip. This figures to be Polanco's final option year. His bat is as major-league ready as it will ever be.