Some players do add power, but I don't think it's particularly normal to have a second career peak with 1.316 OPS, 241 OPS+, and 52 HR/season at ages 35-39.
(His career numbers prior were .968 OPS, 163 OPS+, 32 HR/season—generational, but not break-the-game-of-baseball numbers.)
Posnanski had...