OVR is more indicative of "value" rather than talent, it's a composite. Durability has value. Playing 150-155 games at 100% is better than playing 130-135 games at 100%. Health has value- never going on the DL is better than hitting the DL every 1-2 seasons and losing man-games. Makeup (career longevity) has value. Speed has value; in this instance 50 baserunning kind of counterfeits the 88 speed a bit, but 88-50 is still better than 48-50.
In terms of the defensive matrix, 84 range 75 is pretty bad for a CF, he is slightly below break-even in +/- and would be basically last in the league in fielding percentage for CFs, but on the flipside a .828 OPS is above average for CFs so it balances his WAR a bit. In LF that player would have a much more average bat, but on the flipside would almost definitely win gold glove or be in the top 2-3. The .828 OPS has less WAR in left but the top-notch defense is where the value comes from, hence if you consider all of these factors- 83 OVR.
Not everybody hits 50 HR, not everybody is an MVP, not everybody is all-star. Talent and value mean different things. The season is ridiculously long, playoff series are ridiculously short. For the regular season you want value, for the playoffs you want talent