"Is Maldonado an upgrade over Stassi?
Defensively, not really. Offensively, also not really.
While Maldonado rates as a better thrower and blocker than Stassi, Stassi’s framing is so far ahead of Maldonado’s that it more than compensates. This is best seen in their 2019 metrics. Maldonado has 1.4 framing runs above average, 3.0 blocking runs above average and 0.2 throwing runs above average for a total of 4.6 defensive runs above average in 639.2 innings, per Baseball Prospectus. Max Stassi has 6.6 framing runs above average, -0.3 blocking runs above average, and -0.2 throwing runs above average for a total of 6.1 defensive runs above average, in 210 innings. Stassi has accumulated more defensive runs above average than Maldonado in less than a third of the innings.
But Stassi has been so poor at the plate this year, batting .176. Naturally Maldonado must be an upgrade offensively, right? If Maldonado has been better offensively, the difference is marginal at best. Maldonado has been a poor hitter every year of his career. While Stassi has been offensively putrid this year, he at least has a record of being passable offensively in 2018."
https://www.crawfishboxes.com/2019/7/31/20732006/houston-astros-reacquire-martin-maldonado-but-why-chirinos-stassi-cubs-catcher-trade