The first rule of spring training stats, of course, is that spring training doesn't matter. It doesn't matter in both the sample size sense, where the number of plate appearances or innings in question are too small to base any reasonable judgments on, and in the competitive sense, which is that teams are not playing as hard as they can and they do not care about winning. It might have put Jimmy Rollins in Ryne Sandberg's doghouse for saying spring games are meaningless to the media, but he's not wrong -- teams aren't out to win, and the competition level is different than in the regular season. If this wasn't the case, minor leaguers and non-roster invitees would barely get into the game.

That said, what spring training stats are useful for is figuring out who to keep tabs on around the league during the upcoming season, just to see if they're able to make good on their promising starts. Of the many guys having excellent springs, these are four of the most notable who will be starting the year in the bigs.

Mike Moustakas, 3B, Kansas City

Early in the offseason, the Kansas City Royals traded outfielder David Lough, who picked up most of the slack after the team cut Jeff Francoeur last June, to the Baltimore Orioles for third baseman Danny Valencia. Adding another third baseman focused a spotlight on an issue the Royals and their fans have been wondering about for some time now: When is it fair to give up on Mike Moustakas, a previously highly-touted third base prospect who by the end of the 2013 had authored almost 1,500 plate appearances of merely .681 OPS hitting?

Regardless of what the final answer to that question may be, Moustakas has at least bought himself a bit more time by coming out of the gate hard this spring. Moustakas has put up 43 plate appearances of .486/.558/.943 hitting facing generally quality major league pitching. How do we measure "major league pitching"? Baseball-Reference has an "OppQual" metric which attempts to measure the quality of pitching that a hitter has seen on a scale of 1 to 10, with 1 being a position player on the mound and 10 being an established major league pitcher, and as of Tuesday Moustaka's OppQual this spring sat at 8.6. I'm unaware of any way to index OppQual league-wide to figure out the usual range of values across all batters, but generally the highest this number goes after 10 or so plate appearances is in the low nines. As best as I can tell, the highest hitter so far is Nick Markakis, who sits at 9.2 through 26 plate appearances (and with a 1.142 OPS, thank you very much).

But as the narrative of Moustakas's burgeoning breakout season starts to form, it's important to remember that not only is OppQual little more than napkin-math shorthand -- it treats Kevin Correia, Jose Fernandez and Tim Lincecum all as equal "10" opponents, for instance -- but Moustakas has been here and done this before, finishing the spring in 2013 with an OPS of 1.147 in 76 PA. Then he went on to have the worst season at the plate of his career. He'll be hoping for a different outcome this time around.

Kolten Wong, 2B, St. Louis Cardinals

It is becoming very, very hard to bet against young hitters in the St. Louis Cardinals organization. While most of the weight and expectations of media attention this spring are trained on outfielder Oscar Taveras, who is still not fully returned from the ankle injury that ended his season last year, the most productive new member of the big league club coming up from Triple-A has so far been Kolten Wong, the team's presumptive Opening Day second baseman now that David Freese is an Angel and Matt Carpenter has moved back over to third.

This is quite a reversal of roles from the last time Cardinals fans -- and baseball fans in general -- saw Wong. His season had something of a nightmarish ending in 2013, as the Cardinals called him up in the middle of August and gave him limited but consistent playing time through the end of the year. He responded with 62 regular season plate appearances of .153/.194/.169 hitting -- that's eight singles, a double and three walks in 62 trips to the plate -- and while he made the Cardinals' playoff roster as a reserve out of necessity, St. Louis only gave him six postseason opportunities to redeem himself with his bat. Wong also entered Game 4 of the World Series as a pinch-runner, but was picked off of first base in the ninth inning. He was so bad and Matt Carpenter was so good that some thought the Cards shouldn't mess with something that worked -- keep Freese, leave Carpenter at second and let Wong try to work his way out of the minors again next summer.

Instead, the Cardinals dealt Freese to pick up Peter Bourjos, signed Mark Ellis as a bench veteran/utility player and backup plan and gave Wong a shot at the job out of the gate. He's taken to it quite nicely, with 37 PA of 1.187 OPS baseball and an OppQual of 8.1, which is more or less Triple-A caliber pitching. The biggest reason that 2014 might go better for Wong than 2013 did, however, has less to do with Wong and more to do with Bourjos and Ellis. When Wong was called up last season, the Cardinals were in a playoff dogfight and had a guy with a legit MVP case playing second base every day. Manager Mike Matheny took one look at Wong, a player in that stage of development where he needs consistent playing time every day to maximize his growth, and saw a new defensive replacement, pinch hitter and pinch runner -- three roles very unconducive to consistent playing time.

This year, however, Matheny has Ellis to fill veteran pinch-hitting duties and either Bourjos or Jon Jay (depending on who is starting in center) to sub in for a pitcher on the base paths. As nice as a pretty spring training line is, it's nowhere near as important for Wong's success as the fundamental change in his role with the team could be.

Hector Santiago, P, Los Angeles Angels

There is probably no team that so desperately needs their starting pitchers' fast spring starts to be for real than the Angels do. The top three projected members of the Angels' rotation -- Jered Weaver, C.J. Wilson and Hector Santiago -- have all had good springs to varying degrees; for two of those players that's to be expected, given their history, but Santiago's a bit more of an unknown quality. Los Angeles picked him up the same day they also traded for once-and-future Angel Tyler Skaggs, who they'd originally dealt to Arizona in the deal that brought Dan Haren to town. So far Santiago has been the more impressive in camp, having thrown 16.1 innings of 2.76 ERA ball with 19 strikeouts and six walks -- and his OppQual is 8.9, another impressively high value given the range of talent still involved in this stage of camp. Theoretically all players' OppQuals should trend upwards as roster cuts send more and more minor leaguers back to minor league camp, but the reality of spring training sample sizes factor into that just as much as they do everything else about analyzing numbers from this part of the year.

It's the strikeouts and walks that are most important here, because the big knock on Santiago beyond his lack of a solid MLB track record as a starter is that he walks too many guys -- a career 4.5 BB/9 will not get you very far in the middle of any major league rotation, and that number needs to come down if he's going to be successful. It's far too early to tell if the 3.3 BB/9 he's sporting in camp represents anything other than statistical noise, but if the Angels are going to have any chance of breaking the stranglehold that Oakland and Texas have on the top of the division, they're going to need a rotation that isn't actively hurting the team -- Joe Blanton's inevitable banishment to either the bullpen or waivers (yes, he's been that bad) is a good start, but Skaggs learning on the job in the four spot and Garrett Richards replacing Blanton as the fifth guy is a lot more tolerable if Santiago is a very strong third starter. And if Skaggs also becomes the pitcher prospect-watchers have long thought he could, the Angels could turn the AL West hierarchy on its head.

Yordano Ventura, P, Kansas City Royals

Barring any last minute injuries, the Kansas City Royals will go into the season with a rotation looking like this: James Shields, Jason Vargas, Yordano Ventura, Jeremy Guthrie and Bruce Chen, with Ventura winning the final spot.

Ventura isn't the best starting pitching prospect in the Royals' system -- that's still Kyle Zimmer, who should be arriving towards the middle or end of the year if everything goes as planned -- but he certainly has the best fastball, able to break 100 mph with it when he reaches back, and with great movement on it. Starters can't live on their fastball alone, however, so he had a somewhat doubtful future until his curveball made serious progress over the course of last season. That leaves Ventura with essentially two problems as a pitching prospect, as far as the scouts are concerned: long-standing issues with commanding his pitches, and his short size (Ventura is officially listed as 5-foot-11, and that's probably being a bit generous).

He can't really do anything about the height problem, but as far as pitch command goes he's had a phenomenal spring: 15.1 IP, 1.76 ERA, 15 strikeouts, 1 walk, 1 hit by pitch, 9.2 OppQual. Barring an offseason transformation into 2011 Cliff Lee, Ventura almost assuredly won't be maintaining that kind of a walk rate throughout the season, but overall he's been extremely impressive in a period when he sorely needed to impress and the Royals sorely need him to be impressive.

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All that said, it's still important not to forget the basic, underlying principle of spring training: none of it matters, and none of it is horribly predictive. For instance, last year's version of this article might have included Lorenzo Cain (1.229 spring OPS, .658 season OPS), Brandon Maurer (1.50 spring ERA, 6.30 season ERA), or Lucas Harrell (2.25 spring ERA, 5.86 season ERA). But it also might have included Julio Teheran (1.04 spring ERA, 3.20 season ERA) and Domonic Brown (1.047 spring OPS, .818 season OPS). A good start in spring might not be predictive of success, but it sure doesn't hurt.