With a glaring hole at shortstop, the Atlanta Braves are poised to hand the position over to an untested rookie who has consistently exceeded scouts’ expectations. Tyler Pastornicky worked his way up through the Braves’ system, peaking with a .314/.359/.414 line across two levels in 2011. But while Pastornicky looks like the man for 2012, he has a top-flight prospect right on his heels as Andrelton Simmons enters his third professional season and could be ready for the big leagues next year.

Simmons was the Braves second-round pick in the 2010 draft while Pastornicky was a fifth-rounder for the Blue Jays in 2008. The Braves got Pastornicky as part of the Yunel Escobar trade in 2010. Despite being drafted two years apart, both Pastornicky and Simmons will play the entire 2012 season at 23-years old.

The physical differences between the two players is noticeable. Pastornicky is slightly undersized at 5-foot-11, 170 pounds and he mirrors the description of a scrappy middle infielder. While Simmons is also on the thin side, his 6-foot-2 frame offers a little more projection and the added physicality that scouts prefer.

Both players earned high marks for their effort, but Pastornicky is particularly well-regarded. Scouts have dubbed him as the classic “baseball rat,” noting that he arrives early to the ball park and is among the last to leave. Pastornicky and Simmons are both considered aggressive players who maximize their raw tools through competitive drive and high-energy play.

Beyond the generalities of their physical description and makeup, the two players also have different skill sets that should both play in the major leagues.

Hitting Ability

Scouts initially had questions about Simmons’ raw hitting ability. He overhauled his swing after turning pro, quickening his trigger and simplifying the bat’s path to the hitting zone. The result has been a more complete hitter who has an ability to make easy contact and use the whole field. After hitting just .276 in his 2010 professional debut, Simmons posted a .311 batting average in the Carolina League last year.

Pastornicky’s hands work extremely well at the plate. He gets the bat to the zone quickly and has the feel and ability to adjust his swing as pitches move to the plate. He has a high-level understanding of hitting and this part of this game seems to come naturally. His ability to work with what he’s given is exceptional — and scouts have praised him for his ability to work the ball from line to line.

Both players employ an aggressive approach at the plate. As a result, scouts want Simmons and Pastornicky work deeper into counts and draw more walks. The pair rarely strike out. For their careers, Pastornicky has whiffed in just 11% of his plate appearances; Simmons has struck out in just 7%.

Over the long haul, regardless of role, it’s reasonable to expect that both Simmons and Pastornicky will be above-average — or better — hitters who at least could at least hit in the .270 to .280 range. Given Pastornicky’s consistent profile as a natural hitter — coupled with the prior concerns over Simmons’ hitting ability — Pastornicky earns the slight edge when comparing the hit tool. The edge is extremely minor, though, and may never fully manifest at the big-league level.

Power

Power isn’t a part of either player’s game. Pastornicky is largely a singles hitter who will hit an occasional ball into the gap for a double or a triple. His contact-oriented swing isn’t conducive to lofting the ball out of the park, even if he had the strength for it. During the 2009 and 2010 seasons, I spoke with scouts who were concerned that his lack of strength would result in virtually no power against more advanced pitching. Since that time, he has shown enough ability to drive the ball that pitchers haven’t been able to overpower him.

Simmons doesn’t offer much more power but he does have more bat speed and stronger wrists that generate a little more pop when he barrels the ball. Most of his power comes to the pull side and he showed an increased willingness to turn on the ball in his second professional season. He will never be a significant home-run threat and he’ll struggle to accumulate even a handful each season, but he could rip 25 doubles a year without much trouble.

Though neither player will rely on power as an integral part of their game, Simmons has a reasonable edge over Pastornicky.

Speed

What Pastornicky lacks in power he makes up for in with speed. He’s a true plus-runner and every bit of that speed plays in game situations. He has exceptional instincts on the bases; he reads pitchers well and knows when to push for an extra base. When his raw speed and instincts are combined, Pastornicky could swipe 20 bases a year as an everyday player.

Reports on Simmons’ speed are more mixed than Pastornicky’s. The scouts I spoke with this year turned in everything from average to plus home-to-first times. The three times I saw Simmons play, I had a similar range of times. Even at his best, Simmons’ speed does not play well on the bases. He’s a raw runner who must improve his ability to read pitchers and get good jumps on his stolen-base attempts. With improvement, Simmons could steal 10 to 12 bases a year, but he’ll never be a huge base-stealing threat.

Given both his instincts and consistent, plus-speed, Pastornicky is the clear preference here.

Defense

Discussing the next two tools is where things get really fun. Both players can play defense on the left side of the infield. It is the impressiveness of that defense that separates one from the other.

Pastornicky is considered an average defender with skills that play up because of his instincts. His pre-pitch positioning is excellent and he reads the ball very well off the bat; he gets good jumps to both sides. He has good footwork and soft hands and, while he doesn’t have highlight reel range, he has more than enough for the position.

Simmons, though, is an exceptional defender. He has one of the best shortstop gloves in the minor leagues. His instincts in the field border on other-worldly. He has a tremendous first step that helps his solid foot speed play into at least plus range. He has outstanding hands and the footwork to pull off just about any play. If there’s a fault in Simmons’ defensive game, it’s that he thinks he can make every play and he’ll sometimes force the issue, which can lead to unnecessary errors.

With a potential 70-grade glove at a premium defensive position, Simmons is far above Pastornicky in the field. If the Braves were only looking for a defensive shortstop this year, they could justifiably consider playing Simmons every day.

Arm Strength

Arm strength is the biggest knock against Pastornicky in the field. He does everything else well, but his arm is average — at best — and that holds him back. He’ll struggle on throws from deep in the hole, and he doesn’t always get a lot of zip on off-balance throws — particularly those when he’s ranging up the middle.

Simmons, again, is far superior to his counterpart.. More than a few teams preferred Simmons on the mound entering the 2010 draft, thanks in large part to him lighting up the radar gun during his junior college season. Simmons has touched as high as 97 mph and just about every bit of that translates to the infield. The scouts I sat with at his games this summer were consistently throwing 70- and 80-grades on his arm strength. Without question, those grades give Simmons an edge.

The Pick

The long term-choice between Pastornicky and Simmons comes down to a debate among fans, scouts and industry folks: Do you want the security that comes with Pastornicky, or the risk and potentially high reward that comes with a player like Simmons?

Pastornicky will play in the big leagues and he could have a regular role at shortstop as soon as this season. That said, few scouts I’ve spoken with think he’ll be a consistent first-division regular. Instead, the consensus I’ve gotten is that he’ll be more of a second-division shortstop or top-notch utility player. One scout I spoke with compared Pastornicky to Willie Bloomquist. It’s a comparison that grows on me every time I see Pastornicky in person, but it’s hardly one that elicits visions of stardom and championships.

Simmons’ glove alone will get him to the big leagues, and he has a chance to be a defensive star. How his bat develops is the big question. If he continues to hit for average — even without significant secondary skills — he’ll be a first-division regular who can provide considerable value to a championship-level club. That potential gives Simmons the edge in my prospect evaluations.

When you look at Simmons, you see a player with the potential to make a significant impact on a team’s chances of winning a World Series title. I want that player. Teams want that player. Give me the guy who is going to impact my ability to win at the highest level. I like the guy who can do the little things and is a solid player, but I don’t “love” that guy. That’s reserved for the elite defender with a chance to hit enough to actually matter in the lineup, and that guy is Andrelton Simmons.