Harper Has Fourth Best Monthly OPS+ Ever For A Player 22 Or Younger

Here is the top 20 with 75+ PAs for the month using the Baseball Reference Play Index:

Rk	Player	Month	Year	PA	OPS+
1	Ted Williams	Sept/Oct	1941	101	297
2	Ted Williams	July	1941	80	284
3	Ted Williams	August	1941	157	279
4	Bryce Harper	May	2015	109	279
5	Joe DiMaggio	July	1937	139	277
6	Ted Williams	Sept/Oct	1939	127	265
7	Eddie Mathews	Sept/Oct	1954	97	263
8	Boog Powell	June	1964	86	259
9	Cesar Cedeno	June	1972	127	251
10	Mike Trout	June	2014	102	248
11	Ted Williams	June	1941	125	243
12	Bernie Carbo	May	1970	80	239
13	Mike Trout	July	2012	112	238
14	Pete Reiser	Sept/Oct	1941	114	235
15	Ken Griffey	July	1991	94	235
16	Johnny Bench	June	1970	104	235
17	Johnny Bench	May	1969	77	233
18	Al Kaline	August	1956	131	233
19	Jimmie Foxx	May	1929	121	232
20	Hank Aaron	July	1956	130	231

Now for 23 and under. Harper is 6th. He is in excellent company on each list

Rk	Player	Month	Year	PA	OPS+
1	Ted Williams	Sept/Oct	1942	90	348
2	John Mayberry	June	1972	76	299
3	Ted Williams	Sept/Oct	1941	101	297
4	Ted Williams	July	1941	80	284
5	Ted Williams	August	1941	157	279
6	Bryce Harper	May	2015	109	279
7	Reggie Jackson	June	1969	126	277
8	Joe DiMaggio	July	1937	139	277
9	Ted Williams	May	1942	125	268
10	Ted Williams	Sept/Oct	1939	127	265
11	Dick Wakefield	Sept/Oct	1944	127	264
12	Eddie Mathews	Sept/Oct	1954	97	263
13	Boog Powell	June	1964	86	259
14	Eddie Mathews	June	1955	118	256
15	John Mayberry	Sept/Oct	1972	131	252
16	Alex Rodriguez	May	1999	75	251
17	Rudy York	August	1937	126	251
18	Cesar Cedeno	June	1972	127	251
19	Mike Trout	June	2014	102	248
20	Jose Canseco	Sept/Oct	1988	108	247