I'm pretty sure some season and career figures are getting commingled here 58 PAs with RISP is this year.
I've long been searching for a good way to find an easy source for how a player has done driving in runs relative to their opportunities. The best I've found so far in the game log section of BBRef. For any given year, there's an "RBI opportunities" section that shows how many RBI a player has relative to the MLB average given the number of PAs, as well as the number of PAs with a runner on each base, also relative to the MLB average.
For our friend Matt Wallner, this year his 27 RBI in 291 PAs is below the league average expectation of 33. However, he's also had definitvely fewer opportunities than the average MLB hitter based on who's been on base for his PAs.
PAs with a runner on: First - Second - Third
Wallner: 77-48-17 (142 total, 65 RISP)
Avg MLB: 87-58-28 (174 total, 86 RISP)
In other words, Wallner has had significantly fewer RBI opportunities, and fewer good opportunities, than the average MLB hitter.
So if you think Wallner's driving in fewer runs than his OPS would indicate, you're right!
If you think Wallner's raw RBI total has been suppressed by relative lack of opportunity, you're also right!
Ain't math fun?
I wish they took this a step further and presented the number of RBI Wallner would expect to have given the runners he's had on base. Comparing that number to his actual RBI total would really tell us how effective he's been driving in runs. Effectiveness is better measured by a rate or a comparison of actual vs expected than a raw total. It's why we don't give the batting title to the player with the most hits.