Mattingly's best 5 years in OPS+:
1986 - 161
1985 - 156
1984 - 156
1987 - 146
1989 - 133
Olerud's best 5 years in OPS+:
1993 - 191
1998 - 163
2002 - 140
2001 - 136
1997 - 135
Olerud had two seasons which were better than anything Mattingly ever put up. Olerud's peak (from 1992 to 2002) lasted far longer than Mattingly's too. Just think about this: Mattingly's career high OBP (.394 in 1986) wouldn't even crack Olerud's TOP 7 seasons and is short of Olerud's CAREER AVERAGE.
One more thing:
Career lines in Avg/OBP/Slg:
Mattingly Home - .313/.365/.495
Mattingly Road - .302/.353/.450
Olerud Home - .289/.394/.466
Olerud Road - .301/.402/.464
If Mattingly played his home games at Shea Stadium instead of Yankee Stadium, we wouldn't even be having this discussion.
One more thing: Mattingly wasn't even the best player in HIS DIVISION during his prime. Wade Boggs was a superior hitter those years and played a much tougher defensive position.
Perhaps you are too young or maybe you just aren't aware, but offensive numbers were WAYYYYYYYYYYYY down during the 1980's. They picked up right around the strike year and continued that way for about 10 years. Unfortunately, Mattingly's power was already sapped by 1994 and he was out of the league after 1995.Again, I'll reiterate. Mattingly was THE best offensive first baseman in the game. Olerud? Not so much. It is also why Mattingly has four top-10 MVP finishes and Olerud has one. It's why you can't compare Jim Rice to Vladimir Guerrero, even though each was possibly the most feared hitter of his era. Numbers don't transcend eras, and even though their careers overlapped for awhile, Mattingly and Olerud clearly played in different offensive eras.
For comparison, at the midpoint of Mattingly's career (1989), Fred McGriff's 36 HR led the American League. He was one of five guys with 30+ in the AL. At the midpoint of Olerud's career (1997), Ken Griffey Jr. led the way in the AL with 56. Five guys hit 40+ that year, and 18 players hit 30+. If you can't see the difference there, I don't know what to tell you. Had Olerud played in the 1980's, he's probably a .270-.280 hitter with 12-15 HR and 75 RBI with an OPS far lower than Mattingly.
Comparing Mattingly and Olerud to one another is pointless. Instead, compare them to their peers at the time they played.
About Boggs versus Mattingly. Wade Boggs was a better pure hitter. But if you honestly think that Wade Boggs was ever a better baseball player than Don Mattingly from 1984-1989, then you weren't watching baseball back then. And playing the more physically demanding position isn't as important if you aren't playing it as well. Otherwise, let's bring Mickey Tettleton into the discussion.