(Evan Boyd is a senior studying statistics at the University of Wisconsin-Madison. As a writer and a data analyst, Evan is looking into sports analytics for a career. Evan also is the Station Manager at WSUM 91.7 FM Madison student radio. Feel free to reach out to him at enboyd@wisc.edu for any questions or for a resume, and follow him on Twitter @eboyd42)

40 home runs, and 40 steals. Obtaining this feat in a single season has been done just four times in Major League Baseball history. Four. The first person to do it was Jose Canseco, winning the MVP award in 1988. Barry Bonds, Alex Rodriguez, and Alfonso Soriano are the other three. Steroids aside, these four players were at one point the best players in the league.

Bill James, the father of sabermetrics, combined the number of home runs hit with stolen bases to determine how valuable a player is. He developed what is called the Power-Speed Number, which is the harmonic mean of the two statistics.

Here are the highest Power-Speed Numbers since 2010, singling out one year per player. All but one player (Curtis Granderson) have a WAR above 7.0 – typically considered as near-or-at MVP levels.

                Name  Year    HR Steals     K    BB   WAR PowerSpeed
              (fctr) (int) (int)  (int) (int) (int) (dbl)      (dbl)
1          Matt Kemp  2011    39     40   159    74   8.2   39.49367
2         Mike Trout  2012    30     49   139    67  10.8   37.21519
3    Jacoby Ellsbury  2011    32     39    98    52   8.1   35.15493
4         Ryan Braun  2011    33     33    93    58   7.8   33.00000
5  Curtis Granderson  2011    41     25   169    85   5.7   31.06061
6        Ian Kinsler  2011    32     30    71    89   7.1   30.96774
7       Carlos Gomez  2013    24     40   146    37   8.5   30.00000
8      Carl Crawford  2010    19     47    99    51   7.0   27.06061
9         AJ Pollock  2015    20     39    89    53   7.4   26.44068
10  Paul Goldschmidt  2015    33     21   151   118   8.8   25.66667

The graph shown below (and also interactive here) highlights notable leaders in Stolen Bases, Home Runs, and/or Wins Above Replacement (WAR), from 2010-2015 (if a player was on one of the top lists for multiple years, then their best year in terms of WAR was chosen). Colored in are each players’ WAR.  Highlighted are four areas of high speed, high power, medium speed + power, and high speed + power.

With this data, there is a strong correlation between hitting home runs and stealing bags (-.72). This makes sense; the more home runs you hit, the more likely you are a big beefy dude that can barely run down 1st base, let alone try for 2nd.

If we were to look at the entire dataset since 2010, the line would not be linear but rather some type of inverse function. Since we are looking at the best players at their given talent, the line appears to look more linear. I’ve highlighted four noticeable parts of the data that categorize these types of players.

Red: Faster than Lightning

Notable Players: Juan Pierre, Dee Gordon, Billy Hamilton

Average WAR: 3.33

It is always good to have speed, but it is not always necessary. The players who lead the league in stolen bases have the lowest average WAR. Typically, players like these also hit less for power and walk at a lower rate. This group averages roughly 40 walks per game, which is far the fewest among the other batters. However, their strikeout rate is also the lowest, at 86 per season, making up for their low walk rate.

One player to watch is Jose Altuve, who had 7 home runs and 56 steals in 2014, winning the batting title and snatching a silver slugger award. Suddenly, Altuve has found power in his swing this year, already doubling his home run numbers from 2014, while still batting .341. The only difference is that he is on pace for fewer steals. Because his home run rates are increasing at a faster rate than his decreasing steals, his Power-Speed Number is too increasing, and he is starting to become one of the best overall hitters in the game.

Green: Power to the People

Notable Players: Chris Davis, Miguel Cabrera, Bryce Harper

Average WAR: 5.82

Everybody loves the home run. Not everyone loves the strikeout, though. Take Adam Dunn, for example. In 2012, he hit 41 home runs, the most for him since 2004. He also led the AL in walks (105), but put up an awful 222 strikeouts, and batted just .204.

Playing with home run hitters can be risky. On one hand, there could be a Bryce Harper and Albert Pujols, but on the other side can be Pedro Alvarez and Mark Reynolds. They also can deviate and decline with age. This group averaged 137 strikeouts per season, and because many of them do not even steal a single base, they have the worst Power-Speed Number of any of the groups.

Purple: Defense Wins Championships

Notable Players: Kevin Kiermaier, Jason Heyward, Yadier Molina

Average WAR: 7.16

These are some of the players that will be the best players in the game without anybody noticing. Defense is a much difficult measure to quantify, but can help a team just as much as a power hitter or speed demon. In 2014, Giancarlo Stanton hit 37 home runs, swiped 13 bags, and produced a 6.5 WAR. In 2015, Jason Heyward hit only 13 home runs with 23 stolen bases, but also had a 6.5 WAR. Obviously, there are more factors that need to be added, but sometimes power and defense can have equal importance in winning ball games.

These are some of the players that can be “steals” in drafts, free agency, and trades. They might not be the team leader in stolen bases or home runs, but they will have another part of their game that make them a gem. With the smaller combination of speed and power, they have a Power-Speed Number higher than power and speed leaders (15.87). Since these players are about average at both, they would not be in the top 5 of home runs or steals each year, thus they have such a high average WAR. Two players just above this group are Andrew McCutchen and Dustin Pedroia, two MVP winners.

Blue: The Power-Speed Greats

Notable Players: Mike Trout, Paul Goldschmidt, Ryan Braun

Average WAR: 8.47

Only seven players make up this list, two of them being former MVP’s. The biggest standout is Mike Trout, whose 10.8 WAR during his 2012 rookie season marks as one of the greatest single season performances since Barry Bonds. Matt Kemp was just one home run away from becoming the 5th member of the 40-40 club, as he holds the highest Power-Speed Number since 2010.

Why do these guys stand out? Because when they add speed to their power game or vice versa, they become the best players in their leagues. It is no coincidence that they hold the highest average WAR among all four groups.

Take Paul Goldschmidt – a power hitting first baseman who can drive the ball to all parts of the field. What makes him stand out and become the best first baseman in baseball is by playing good defense, hitting for contact, and being quick on the bases. A first baseman that can give you 20 steals a season is significant. Hence, when comparing Goldschmidt to another guy on our list, Paul Konerko, Goldschmidt stands out more, having an 8.8 WAR that nearly doubles Konerko’s best year. It is the extra things, like stealing bases, that make him stand out.

When observing each players’ best year by WAR, many of them who led the league in home runs had career highs in steals, and vice versa. A year with 40 home runs and 10 steals might not be as valuable as a year with 33 home runs and 20 steals. When scouting for players with both tools, it can produce incredible success.

I’ve attached my code in a git repository.