I meant to post this last night, but the net was down here.
First, his on-base% was .398 and his relative on-base% was 1.236.
Evans was first at .402 but only had a relative ob% of 1.196.
Harrah was next at .398 but also lower in relative OB% at 1.213.
And looking down the list, he lead all players in relative OB% which has to count for something.
Second, his OB% was walk heavy-yes, but this also means that his very good OB% took place over more plate appearances than his below average slugging%. His OB% was over 656 plate appearances while his slugging was only over 536 at bats meaning that his OB% should probably be weighted by that proportion when making evaluations. Because of this, walk heavy OB% are not worse than hit heavy OB% for players who have below average slugging percentages. (see what I'm saying?)
Third, if you mess around with run expectancies just slightly, you can come up with very different net values for steals and CS.
Basically, excluding the added cost of making outs, a steal is worth about as much as the loss of a base-runner from first base.
Different evaluations may put a steal of second at as high as .25 runs and as low as .19 runs and an eliminated runner at as low as -.25 runs and as high as -.39 runs.
An out, in his run scoring environment would also be about -.18 and if one uses a higher run scoring environment it might go as high as -.22 which is not accurate in this case.
So using the most favorable scenario, his 130 steals were worth +32.5 and his CS and outs about -18 for a net of 14 runs. Also 14 runs in that run scoring environment would be equivalent to over 4 games worth of offense. 12-15 games worth of offense above replacement would be a top MVP contender season.
Using the worst case scenario, his 130 steals were worth only about 24.7 runs (though your numbers are a little lower) and his 42 CS about -23.9 for a net of merely +.8 runs.
Another way to look at it is that a SB is almost as valuable as turing a single into a double, and a CS is about the same as eliminating a walk, and adding an out. A SB is actually probably worth almost exactly the same as .7 extra bases with an average breakdown of double, triples and home-runs. A CS is so close to equal to eliminating a walk and adding an out that I will leave it at that.
So if we want to modify his on-base and slugging percentages to include his base stealing numbers he would have 205 TBs + 91 equivalent due to steal or 296. We would also remove 42 walks giving him 74, and add 42 outs giving him 435.
This would give him effective slugging percentage of .512 and an effective on base% of .332 (though you could discredit the walk at a different rate from slugging instead). This would mean that his effective OPS+ would be 133, but could be as low as 127 if you dock him differently from different components of OBP and SLG%.
So I think its safe to say that it was along the lines of a straight up 127-133 OPS+ season which, for a corner outfielder who was probably a little above average would be more than mediocre but fairly far from MVP caliber though:
A good base-stealer would have, in theory, a better likelyhood of producing more leveraged value stolen bases due to situations, and we can't discount that he had good speed on the bases which didn't show up in the regular stat line (he only had 5 GIDP). We also can't discount his specific disruption factor on the bases.
Anyway in post script
I would place a SB at about .25 runs and a CS in his era at about -.53 for the loss of baserunner and the out. A loss of baserunner can't be more than equivalent to a walk which is about .36, and an out cuts out the average production of a typical hitter. If you use bases, a plate appearance is worth about .36, or about .18 runs, but if you look at the runs per plate appearance in the league, it was only about 4.3/25.5 or about .17, so I think that an out is inappropriately docked in that era. An out only costed .17 runs and that is a fact. If the run expectancy is off, it is off.
His steals and CS, in raw terms only were probably worth 10 runs, or 2.4 games worth of offense, and again that is significant.
Put most simply, it would be about the same as turning 10 singles into home runs. That would give him again an estimated 133 OPS+.
IT WAS PROBABLY VIRTUALLY IDENTICAL IN VALUE TO ANDRE DAWSON'S '87 SEASON.
Comparable to Don Mattingingly in '88 and '89 (even if you discount Henderson's speed when not running).
About equal to the value that Pete Rose averaged for the '70s in which he was voted player of the decade.
Better than Jim Rice in '83 when GIDP are factored in and much better than Rice in '75 when he was runner up MVP.
About equal to David Ortiz in '04.
About equal to Griffey in 2000.
Those are the ones that it is safe to say that for.
MEDIOCRE-if you mean mediocre among seasons by hall of famers yes, its probably a straight down the line average season among all seasons produced by hall of fame caliber players.