Spd: Scoring speed among top prospects

Speed is best measured by a stopwatch. Determine a distance, clock how long it takes someone to run that distance and compare it to others. Simple enough. It's why the Olympic 100-meter dash is one of the more important sporting events of our times. We want to know which man and woman is the fastest on our planet.

But what about baseball, where there is no watch -- outside of the ones in scouts' hands or in MLB.com's Statcast -- and the effectiveness of speed is more than just beating someone past an arbitrary line?

Enter Speed (Spd) Score. 

Speed Score was developed by Bill James in the late 1980s to evaluate how effective position players are at using their quickness to affect the game. The formula uses stolen bases, times caught stealing, triples, runs scored and a few other numbers, and boils all of that down to an easier-to-understand rating on a 0-10 scale. We went through the four components of Speed Score last winter, but here's a quick reminder on them with a thankful nod in the direction of FanGraphs' David Appelman for his breakdown of the exact formulas:

• Stolen Base Percentage: Pretty much exactly as it sounds. How good is the player at stealing a base once he decides to go?
• Frequency of Attempts: It's one thing to be perfect in stolen bases. But if perfect means 1-for-1, that doesn't tell us much. Speedy players are more likely to attempt to steal bags each time they get on base. This gives us an idea of just how often they do take off.
• Percentage of Triples: If you've watched the game, you know guys with speed can sometimes turn singles into doubles, doubles into triples, triples into inside-the-park homers. Triples are most closely associated with speed and more frequent than inside-the-parkers, so this measures how often a player turns balls in play into triples.
• Runs Scored Percentage: By the same token as above, speedy players are more likely to wheel around the bases and score runs. If you've seen a slow player get stopped at third for fear he'll be gunned down at home, you know what I'm referring to.

Take the average of those four components and, boom, you have your Speed Score. For context, 4.5 is considered an average score with 7 being excellent and 2 being, according to FanGraphs, "awful." Detroit's Anthony Gose led the Majors in 2015 with a 7.5 Spd while David Ortiz was last at 0.9. So that's what we're dealing with here. 

As we did with ISO in a Toolshed, let's take a look at the best and worst Speed Scores among top-100 prospects during the 2015 season. Speed Scores for all top-100 prospects are found in this table.

Moncada, the top prospect in the Red Sox system, became a meme last month when a tweet showed him looking like the Cuban Hulk, but let this serve as a reminder of just how fast the 20-year-old is as well. The Sox allowed him to turn on the jets late in the season at Class A Greenville with 45 of his steals coming in his final 56 games, the other four coming in his first 25 contests. His high frequency of stolen base attempts and high success rate shine brightly when it comes to Spd.

Same goes for Mateo, who led the Minors with 82 steals and only finished second here because of a smaller stolen base and runs scored percentages. Margot gave the Red Sox two prospects in the top five until the speedy center fielder was shipped to San Diego in the Craig Kimbrel trade. Anderson, who posted a 7.3 Spd in 2014 when he was limited due to 84 games by a hand injury, had no issues burning rubber in his first fully healthy season in the White Sox system. As for Cameron, we'll get to him in the expectations portion below.

No huge surprises here either, except for McKinney who we'll also get to in a bit. 

Neither Smith, who otherwise enjoyed a very good season at Class A Advanced St. Lucie, nor Stephenson tripled even once in 2015, making them the only two top-100 prospects without a three-bagger on their resume. In Spd, a zero in one of the four components hurts big time. In fact, Stephenson, who earns his highest marks on the defensive side behind the plate, had two zeros as he didn't notch a stolen base either, but he finished with a slightly better score on account of his frequency of stolen base attempts and his runs scored percentage. Both prospects are considered 40-grade runners on the 20-80 scale.

Gallo is an interesting case because, though no one considers him to be fleet-a-foot, a 2.8 Spd feels extremely low, esepcially after he posted a 5.1 in 2014. What's more, he had a 6.9 Spd over the smaller sample of 36 games in the Majors, so something seems a little off. A theory: Gallo's power "hurts" him here in that his strength pushes a decent amount of possible triples over the fence for homers, and with only 18 of his 41 runs coming after non-homers, he might have been hurt by a Round Rock offense that ranked 13th out of 16 in the PCL in runs scored.

Mazara is curious as well, being one of two outfielders in the bottom five, but the No. 2 Rangers prospect's value has always come from his bat and arm in right field. Texas has rarely pushed him to steal with only 12 steals to his name in four Minor League seasons.

The expectations game

We've referenced them a little bit, but thanks to MLB.com's scouting grades, we can directly compare Speed Scores to how we'd expect prospects to perform based on their run tool. As we've done in the past, we'll use mean and standard deviation to get everything on similar scales. The mean Speed Score was 6.0 with a 1.78 standard deviation while the mean run tool grade was 54.4 with an 11.24 standard deviation. If both of those means seem higher than what's normall considered "average," then you're absolutely correct. Just remember that our pool of players here are top-100 prospects, i.e. guys who are considered to be especially good talents, and the results here reflect that.

Cameron, the No. 37 overall pick in this year's Draft doesn't exactly have blazing speed, but he uses what he has to great effect. He attempted 34 steals in 51 games between the Gulf Coast League and Greeneville of the Appy League and was successful in 24 of those attempts. Only Clark, with 25, had more steals among 2015 Draftees ranked in the top 100. 

In fact, four out of the five listed here were taken in the 2015 Draft and only played essentially half a season in the Minors this summer. So, sure, there might be some small sample noise going on there, but what's more likely is that these high picks got ample chances to show off what speed they do have at lower (read: less-experienced and less-talented) levels and took full advantage. Keep an eye on all four and see if their Spds dip back closer to expectations when they make their full-season debuts in 2016.

As for Kepler, the Twins' No. 6 prospect swiped 19 bases and produced 13 triples in the Minors during one of the breakout seasons this year. In his four previous seasons combined, he had only 22 steals and 18 triples, so perhaps a run tool upgrade will be in the offing when rankings are updated this winter.

For your amusement, here are the five full-season prospects who most outperformed expectations based on run tools:

The most interesting among that group is Reed, who owns the lowest run tool grade at 30, meaning expectations were nearly as low as possible when it came to speed. Yet he tripled five times and led the Minors with 113 runs scored -- a number aided plenty by his time with a great offense in Lancaster -- so Spd shined a little more brightly on him than you'd think.

As for those who underachieved...

As a player with time at center field on his resume, you'd have guessed that McKinney would have sported a Spd well-above the "awful" level. Instead, he went 0-for-2 in stolen base attempts and scored just a 4.33 for runs scored percentage, second-lowest ahead of only Gallo. Dating back to his days in the A's system, McKinney has typically posted average Spds in the 4's and 5's at each of his stops, so we'd hesitate to say this year's rating is anything more than outlier. Just don't think he'll ever be a double-digit steals guy going forward.

The other four above are victims of extremely high expectations. Peraza led top prospects with a 9.0 Spd last season before settling back to a still-solid 7.6, thanks to 35 fewer steal attempts, while playing for two different organizations. Buxton and Turner are also considered elite, and indeed Buxton's presence here feels harse after he posted Spd that was sixth-highest among top-100 prospects. But as one of only two prospects on the top-100 list with a perfect 80 grade on his run tool, the math expected more, though that's nothing to worry about. 

As for Swanson, this year's top overall pick did not attempt a stolen base, perhaps as a way of protecting himself after suffering a facial injury and a concussion as a result of being hit in the face during a simulated game in July. The D-backs shortstop, who went 16-for-18 on the basepaths in his final year at Vanderbilt, scored high on the runs and triples components and can be expected to run a lot more in 2016.