Wednesday, December 26, 2018

How big was Bryce Harper's decline after his great season in 2015?

In 2015, at age 22, Harper had a 198 OPS+. The only player to have a higher OPS+ at age 22 or younger was Ted Williams with 235 in 1941 (the year he batted .406). And Ty Cobb is the only other player in this age group to reach 190 with 193 at age 22.

To look at how great young hitters did in the years immediately after their high OPS+ season, I had the Baseball Reference Play Index call up all the players age 23 or younger who had at least a 170 OPS+  with a minimum of  400 PAs.

The table below shows what they did at either age 22 or 23 and then the next three seasons. Avg is actually their OPS+ over the next three years combined, not a simple average.


Player OPS+ Age Yr.1 Yr.2 Yr.3 Avg
Albert Pujols 187 23 173 168 178 173
Arky Vaughan 190 23 148 133 141 141
Boog Powell 176 22 112 158 104 126
Bryce Harper 198 22 114 156 133 133
Eddie Collins 170 22 150 162 158 157
Eddie Mathews 171 21 172 170 143 161
Eddie Mathews 172 22 170 143 154 156
Eddie Mathews 170 23 143 154 120 139
Frank Thomas 180 23 174 177 212 186
Jimmie Foxx 173 21 161 140 207 171
Joe Jackson 193 23 191 192 156 181
Jose Canseco 170 23 147 159 157 156
Ken Griffey Jr. 171 23 171 122 154 153
Mel Ott 174 23 138 168 157 155
Mickey Mantle 180 23 210 221 188 206
Mike Trout 179 21 168 176 172 172
Mike Trout 176 23 172 186 199 185
Reggie Jackson 189 23 127 144 149 141
Stan Musial 177 22 174 183 134 163
Stan Musial 174 23 183 134 200 173
Ted Williams 235 22 216 215 205 212
Ted Williams 216 23 215 205 189 203
Tris Speaker 170 22 157 189 182 177
Ty Cobb 193 22 205 196 200 201
Ty Cobb 206 23 196 200 194 197
Willie Mays 175 23 174 146 173 165

There are 26 cases but some player appear more than once (Mathews, Trout, Musial, Williams, Cobb). So if we only look at the number of players instead, we have 20 cases. 13 of those 20 players had at least one season of a 170 OPS+ or higher in the next three years (starting from the first season they did it-Mathews did it first at age 21 and did it again at age 22 & 23 but not at 24, 25 or 26).

So most young players who have a great season have another one pretty soon after. Not Harper. His best season of the next three is 156.

The next table shows the difference between each player's great young season and the average of the next three, sorted by largest gain down to biggest decline.

Player OPS+ Age Avg of next 3 seasons Diff
Mickey Mantle 180 23 206 26
Mike Trout 176 23 185 9
Ty Cobb 193 22 201 8
Tris Speaker 170 22 177 7
Frank Thomas 180 23 186 6
Stan Musial 174 23 173 -1
Jimmie Foxx 173 21 171 -2
Mike Trout 179 21 172 -7
Ty Cobb 206 23 197 -9
Eddie Mathews 171 21 161 -10
Willie Mays 175 23 165 -10
Joe Jackson 193 23 181 -12
Eddie Collins 170 22 157 -13
Ted Williams 216 23 203 -13
Albert Pujols 187 23 173 -14
Jose Canseco 170 23 156 -14
Stan Musial 177 22 163 -14
Eddie Mathews 172 22 156 -16
Ken Griffey Jr. 171 23 153 -18
Mel Ott 174 23 155 -19
Ted Williams 235 22 212 -23
Eddie Mathews 170 23 139 -31
Reggie Jackson 189 23 141 -48
Arky Vaughan 190 23 141 -49
Boog Powell 176 22 126 -50
Bryce Harper 198 22 133 -65

So Harper has the biggest drop off and he seems well ahead of the next biggest decliner, Powell. Considering how well he did at age 22 and where that ranks historically for young hitters, his performance the last three years may look disappointing.

I also looked at all players who had 1200+ PAs from ages 20-22 and an OPS+ of at least 140. Then I found their OPS+ over the ages 23-25 (not exactly, for example, Ted Williams missed three years in WWII so for him I just used his next three seasons).

Harper had an OPS+ of 154 over ages 20-22 and 133 over ages 23-25. That drop off of 21 is the 2nd biggest among this group of 22 players. In fact, 16 of the 22 actually did better over the next three seasons and the last time anyone dropped off as much as Harper was in the 19th century (Beckley). Pujols, Griffey and Trout are all fairly recent players who increased their OPS+ going from 20-22 to 23-25. Yet Harper has this big decline.

Player OPS+ 20-22 OPS+ 23-25 Diff
Mickey Mantle 155 203 48
Ted Williams 182 212 30
Ty Cobb 176 201 25
Tris Speaker 152 177 25
Rogers Hornsby 153 177 24
Jimmie Foxx 162 184 22
Albert Pujols 154 176 22
Denny Lyons 147 164 17
Joe DiMaggio 147 163 16
Ken Griffey Jr. 146 161 15
Giancarlo Stanton 140 151 11
Mike Tiernan 146 154 8
Mike Trout 172 178 6
Sherry Magee 145 150 5
Mel Ott 156 160 4
Eddie Mathews 153 156 3
Fred Carroll 142 141 -1
Stan Musial 166 163 -3
Sam Crawford 145 141 -4
Al Kaline 140 129 -11
Bryce Harper 154 133 -21
Jake Beckley 142 119 -23

Where does Harper's 133 OPS+ rank all-time among 23-25 year olds who played at least half their games in the outfield with 1200+ PAs? 81st out of 99.

Click here to see that list

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