A Favorite Toy Update for Career Homersby David Marasco Last year we looked at "Favorite Toy" predictions for home runs. Bill James made up a rough-and-ready prediction system he called the "favorite toy." The idea was to predict if a player could hit a certain milestone in a given stat. Suppose that Joe Ballplayer was at 2500 hits, what were his chances at getting to 3000? James reasoned that if you could be expected to get 500 hits based upon your previous stats, then you had a 50/50 chance of getting those 500 hits. In more general terms, he set the probability of getting to a certain milestone as (expected/needed) - 0.5. In other words, if you could be expected to get 50 more home runs, and you needed 100 for the milestone, then you had a 50/100- 0.5 = 25% chance of doing so. But how many events could be expected? James realized that there were two components to this. The first was a rate, and he felt that a weighted average of (3*last year + 2* one year prior + 1* two years prior)/6 was the proper rate. In addition to this, James estimated remaining career by assuming that a 20-year-old had 12 years left, and subtracted .6 years for each year actually used. In other words, a 30-year-old has used 10 years, so subtract 6 from 12 to get an additional 6 years expected in the career. You never have fewer than 1.5 years left, no matter what your age. Here we use the age the player was on July 1. As a limiter to extreme cases (both due to young players and players very close to the milestones), James included a .97^n ceiling where n is the number of years the player would need to play at the established rate. Here we've taken the home run numbers for a selection of players from the 2002 season. From there we've used Favorite Toy to estimate their odds for various homerun milestones.
Barry's place with the greats is already well-established. Who knows how many homers he will hit if they actually pitch to him?
Junior's recent injury problems have really put a kink in his chances. Of course, a player with a injuries is the exact type of prediction that this system will underestimate. Three years of Classic Griffey will put him past 600. Is there really only a 15% chance that we'll see the return of Junior?
A few years back the thought that Sammy was almost a mortal lock to pass Mays would have made one laugh. A 50/50 for Ruth? That seems a little hard to believe, but Sammy has really stepped up his game.
The most underlooked slugger of his generation will certainly finish with 500 homers. Given his age, 600 is a stretch, but it's not out of the question.
Manny slowed down a little bit last year. Still, he has a decent shot at not only 500 homers, but also 600.
A-Rod with a 38% chance of hitting 800 dingers? It seems crazy, but he's been hitting about 50 a year, and ten years from now would place the youngster in his mid-late 30s. If he stays healthy, he can take advantage of the DH rule to set records that will never be broken.
Again, the 15% chance at 700 should be taken with a grain of salt, after all, he has only 200 at this point.
Some older contenders have dropped off the radar. McGwire retired, Fred McGriff doesn't have much time
left, and Juan Gonzalez's injuries have slowed him down. Still, we have Bonds and Sosa in the next few
years and the promise of A-Rod and Vlad. Will Aaron's record still be standing a decade from now?
Only time will tell.
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