Toolshed: Whose hot start will hold up?

This is part of a series of Friday columns we're calling the Toolshed, focusing on some of the more interesting prospect-centered storylines as the 2015 season develops. Have ideas, feedback questions for Sam, email him or tweet him @SamDykstraMiLB.

Saturday marks the close of the first full month of the Minor League season, and that gives us a good excuse to check in how prospects have done in their new (and sometimes old) surroundings.

We're already developing storylines on who's coming out of the gate quickly and who has stumbled a bit based on regular statistics (batting average, home runs, stolen bases, ERA), but obviously there are other ways to evaluate. Some player's hot streaks might not be what they seem, while others' rough stretches could be due for a bounceback soon enough. Still others might be playing just as well, or even better, than their strong stats already indicate. In other words, think back to the offseason when we covered FIP, BABIP, ISO and Spd score.

Earlier this week, we rolled out the first edition of Crooked Numbers on some of the quirkier stats from April, so consider this its prospect-focused cousin. (Note: all numbers included here are as of the completion of Wednesday's games.)

As good as advertised

Carlos Correa, SS, Astros, Double-A Corpus Christi: Let's start with an easy one. With the Kris Bryant drama now over, the next "When will he be called up?" questions being asked about an ultra-prospect involve Correa. That's for good reason. MLB.com's No. 3 overall prospect is batting .382/.457/.706 with six homers and 28 RBIs through his first 25 games in the Texas League. That's especially impressive given that his six homers already equal his 2014 total at Class A Advanced Lancaster (in the hitter-happy California League, we might add) in 37 fewer contests.

Consider this as well: Correa's .324 ISO (isolated slugging percentage; i.e., slugging percentage minus batting average) is tied for the highest among all Double-A hitters. When he's making contact, it's been very loud contact. We'd expect that from a player whose been given a 65 power grade from MLB.com, but using the numbers from a season ago, he's performing closer to a player with a 75 grade in that department. That's an incredible jump from a 20-year-old player who had a .185 ISO last season. 

Because I'll discuss BABIP (batting average on balls in play) later, I'll mention that Correa's .440 BABIP is awfully high, but it's not astronomically out of the norm coming from a fast shortstop who had a BABIP of .373 in 2014 and .375 in 2013. In other words, that .382 average might be a little high, but the power, well, that is quite real. With Jed Lowrie out until the All-Star break and his replacements in the Majors underwhelming, general manager Jeff Luhnow has already said Correa will be up at Triple-A Fresno in the near future and a trip to Houston might not be far behind.

Roman Quinn, OF, Phillies, Double-A Reading: We knew the Phillies' No. 4 prospect was fast. He earned an 80 grade from MLB.com for his run tool this offseason after he stole 30-plus bases for a third straight season in 2014. The Phillies also moved him from shortstop to center field, because his speed will play out there and they didn't want him bumping into top prospect J.P. Crawford.  

And if you thought a move to Double-A would slow the 21-year-old down, think again. He's swiped 11 bags and added five triples in 25 contests. Those are good on their face, but when thrown in with a few other factors (frequency of stolen bases, stolen base success rate, runs scored percentage, among others), you'd see he has a 9.3 Speed Score, making him the only player in Triple-A or Double-A to post a number higher than 9.0 on the stat that uses a 0-10 scale. That beats out Byron Buxton (8.8), Travis Jankowski (8.8) and Mallex Smith (8.7), each of whom also have 70-or-above running grades. Only Jose Peraza put up a Speed Score higher than 9.0 last season, and Quinn's number itself was just 7.2 (although that came after he missed time due to a ruptured Achilles, which may have caused the brakes to be applied early on). 

One thing is for sure: one of the Minors' fastest players is back to burning rubber.

Eduardo Rodriguez, LHP, Red Sox, Triple-A Pawtucket: We now pivot to pitching, a topic Red Sox fans might try to avoid these days given the state of the Major League staff. Since the start of the season, the hope has been that a stacked Pawtucket rotation might help at some point. Rodriguez, acquired last July from the Orioles for Andrew Miller, is closer to making that hope a reality. The 22-year-old left-hander, who owned a 0.96 ERA with 39 strikeouts in 37 1/3 innings at Double-A Portland after the deal last season, has carried that momentum to the International League, where he is 3-0 with a 1.82 ERA through four starts (24 2/3 innings).

Where our interest perks up here is with FIP (fielding independent pitching), which takes into account only strikeouts, walks and home runs allowed -- the things a pitcher can most control. With an 8.0 K/9, 0.7 BB/9 and 0.36 HR/9 early on this season, Rodriguez has a 2.30 FIP, lowest among all Triple-A hurlers. The walks are particularly impressive. Rodriguez has issued a walk to only 2.2 percent of hitters. That's less than one-third lower than his career rate of 7.7 percent. 

If you can limit your walks and get a good amount of strikeouts, FIP will smile upon you, and Rodriguez, whose K/BB rate is 22-to-2, certainly fits the bill. The southpaw is on the Red Sox 40-man roster, and if he can continue to show plus control with an above-average fastball-changeup-slider mix, a Major League debut might not be too far off.

Due for regression

Carlos Sanchez, 2B, White Sox, Triple-A Charlotte/Trevor Story, SS, Rockies, Double-A New Britain: We're grouping two of the Minors' hottest hitters together because their numbers tell awfully similar tales. Story, the Rockies' No. 13 prospect, ranks second in all the Minors with a .396 batting average -- while we're focusing on average here, we'll add that he leads with a crazy .504 OBP -- with Sanchez checking in at eighth with a .379 average. Though both of those numbers are eye-popping from the two middle infielders, they should be taken with some grains of salt, considering the following:

Story leads all Double-A hitters with a .517 BABIP, meaning over half of his balls put in play have fallen in for hits. Sanchez isn't too far behind with a .487 BABIP. Although it's mostly associated with luck -- i.e., how many times a ball squeaks by defenders -- BABIP can mean any number of things, particularly for hitters. Fast players are more likely to have higher BABIPs as are players who make consistently hard contact. Neither Story nor Sanchez is considered especially quick, and though Story has an impressive .308 ISO, Sanchez's .162 number points to fewer hard-hit balls.

The fact remains that both Story (career .354 BABIP) and Sancez (.346) are seeing a few more balls fall than they normally would. Out of the two, you should be more bullish on Story continuing to rake, but don't be surprised to see either's average dip in the next few weeks as their BABIPs move closer to their career norms.

Jon Gray, RHP, Rockies, Triple-A Albuquerque: There was a time this spring when Gray was considered for a starting spot in the Rockies rotation out of Spring Training. That might feel like a long-lost memory for Rockies fans now that the 2013 third overall pick has put up a 9.13 ERA and 2.03 WHIP through his first five outings (22 2/3 innings) at Triple-A Albuquerque. Those numbers do come in the hitter-friendly Pacific Coast League, but they're ugly in any league. 

But Gray's season ERA and WHIP probably deserve to look a whole lot better. With 19 strikeouts, nine walks and two homers allowed in 22 2/3 innings, the 23-year-old owns a 4.42 FIP. So, though his 9.13 ERA is the highest among PCL qualifiers, his 4.42 FIP isn't among the 25 worst in the circuit. In fact, his 4.72 difference between ERA and FIP is the biggest gulf between the two stats in the entire Minors. 

A .443 BABIP -- highest for opposing batters of any pitcher in the PCL -- has shown that his Isotopes defenders haven't done a terribly great job backing him up. Looking at his BABIP separately, we could say Gray is serving up meatballs that opposing hitters are finding easy to hit. Taking the stat with his FIP, we know he's done an alright job at controlling what he can, meaning his ERA should be much lower than 9.13. That might not provide much comfort for Rockies fans, but at least it's something.

Odds and ends

• For those hoping Reds top prospect Robert Stephenson would have a more successful start in his return to Double-A Pensacola, think again. The 22-year-old right hander has a 6.85 ERA through 23 2/3 innings, and because of a 6.9 BB/9, his 5.23 FIP is third-highest in the Southern League. 
• Peter O'Brien's Major League prospects are pretty much based solely on his power, and he's had that in spades so far at Triple-A Reno. The 24-year-old catcher-turned-outfielder ranks third in the PCL with a .347 ISO. That's even higher than the .323 he put up between the Yankees and D-backs systems in 2013, when he hit 34 homers in 106 games. O'Brien has eight homers in 26 contests thus far.
• As with Gray but to a lesser extent, top Angels prospect Andrew Heaney's 4.15 ERA (which includes five innings from a suspended game Wednesday) doesn't jump out at you. But thanks to a solid strikeout rate and continued control, his FIP stands at just 3.06, third-best in the PCL behind only Mets prospects Steven Matz (2.74) and Noah Syndergaard (2.93).