Clay Dreslough
08-07-2002, 04:32 PM
Bill James has a formula he calls "The Favorite Toy" for determining the chance of a player hitting a career milestone:
This example is for Barry Bonds, and his pursuit of Hank Aaron's lifetime home run total. His current number of homers are representative to the end of the 2001 season.
The Favorite Toy takes four things into consideration in calculating the information:
1. The number of Home Runs that Barry Bonds needs to reach his goal. This is simply his goal number of Home Runs minus his current number of home runs.
2. How many years Barry Bonds has left to reach his goal. This is estimated by the formula, 24 minus .6 times the player's age. This assigns a 20 year old twelve remaining seasons, a 25 year old nine remaining seasons, a 30 year old six remaining seasons, and a 35 year old three remaining seasons. Any player who is still playing regularly is assumed to have a minimum of 1.5 seasons remaining. For Barry Bonds, age 37, his years remaining value is 1.8.
3. Barry Bonds' estimated home run level. This is estimated as 1/2 of what he did last year, 1/3 of what he did the year before, and 1/6 what he did the year before that. With 73 homers last year, 49 the year before, and 34 the year before that, Barry's estimated home run level is (36.50 + 18.34 + 5.66 = 60.5).
4. Barry Bonds' projected remaining home runs. This is found by multiplying how many years he has left to reach his goal by his estimated home run level. This is 1.8 x 60.5 = 108.9.
Once Bonds' projected remaining home runs are found, the chance of reaching his goal is his projected remaining home runs divided by the number of home runs he needs to reach his goal, minus .5. Barry started 2002 with 567 home runs, needing 188 to reach Hank Aaron. (108.9 / 188) - .5 = .079 = 7.9%
Note: No player's chance of reaching a goal can be more than .97 (97%).
BTW, if Barry finishes this year with 50 homers. His new projected number will be 57.5 per year, with 1.5 years remaining (the minimum for an active player), for a total of 86.25 more homers before he retires, but only 138 needed to tie Hammerin' Hank. The yields a 12% chance of reaching 755.
Clay
This example is for Barry Bonds, and his pursuit of Hank Aaron's lifetime home run total. His current number of homers are representative to the end of the 2001 season.
The Favorite Toy takes four things into consideration in calculating the information:
1. The number of Home Runs that Barry Bonds needs to reach his goal. This is simply his goal number of Home Runs minus his current number of home runs.
2. How many years Barry Bonds has left to reach his goal. This is estimated by the formula, 24 minus .6 times the player's age. This assigns a 20 year old twelve remaining seasons, a 25 year old nine remaining seasons, a 30 year old six remaining seasons, and a 35 year old three remaining seasons. Any player who is still playing regularly is assumed to have a minimum of 1.5 seasons remaining. For Barry Bonds, age 37, his years remaining value is 1.8.
3. Barry Bonds' estimated home run level. This is estimated as 1/2 of what he did last year, 1/3 of what he did the year before, and 1/6 what he did the year before that. With 73 homers last year, 49 the year before, and 34 the year before that, Barry's estimated home run level is (36.50 + 18.34 + 5.66 = 60.5).
4. Barry Bonds' projected remaining home runs. This is found by multiplying how many years he has left to reach his goal by his estimated home run level. This is 1.8 x 60.5 = 108.9.
Once Bonds' projected remaining home runs are found, the chance of reaching his goal is his projected remaining home runs divided by the number of home runs he needs to reach his goal, minus .5. Barry started 2002 with 567 home runs, needing 188 to reach Hank Aaron. (108.9 / 188) - .5 = .079 = 7.9%
Note: No player's chance of reaching a goal can be more than .97 (97%).
BTW, if Barry finishes this year with 50 homers. His new projected number will be 57.5 per year, with 1.5 years remaining (the minimum for an active player), for a total of 86.25 more homers before he retires, but only 138 needed to tie Hammerin' Hank. The yields a 12% chance of reaching 755.
Clay