He has a 10-8 post season record and took his two teams to the playoffs 10 times in 15 years. Yea, I'm on board with that.
The indisputable record clearly reveals that MM was somehow able to "take" his team to the playoffs during 9 of his 13 years as head coach in Green Bay (and has now done so during 1 of his 2 seasons in Dallas).
However, the assertion (or hope?) that MM has "EXCELLED" as a coach in the playoffs (as posited by the original poster) might not be as indisputable, at least among less discerning observers of the NFL.
Less knowledgeable NFL fans might point out that while MM "took" GB to the playoffs 9 times he had hall of fame QBs behind center during each of his 13 seasons as the Packers coach and thus that getting to the playoffs <70% of the time while in GB was not really all that excellent of a record.
Such less knowledgeable fans might even contend that making the playoffs by having a better record most years than the Lions, Vikings, and Bears was perhaps not the greatest of coaching accomplishments given that those franchises were not very good when it comes to winning football games during MM's tenure in GB.
Truly ignorant fans might even reference MM's 1-5 playoff record against teams from the typically much stronger, more competitive NFC West as evidence that he did not actually EXCEL as a coach in the playoffs.
Unfortunately, those questioning whether MM truly EXCELS in the playoffs are likely to be the same type of fans who don't properly appreciate what a great accomplishment it was for MM to overcome so many roster obstacles and "take" the Cowboys to the playoffs in 2021.
I mean having a better record (with Dak at QB) than the Daniel Jones/Mike Glennon led Giants, Taylor Heinicke led WFT, and Jalen Hurts/Gardner Minshew led Eagles screams excellent coaching, does it not?
In any event, should be fun to see MM EXCEL coaching the Cowboys during the upcoming playoffs just like he did in leading Favre-Rodgers to all of those SB appearances while he was up in GB.