What's his playoff record since 2015?
There you go, cherry picking again. That is like asking what Belichick's playoff record is since 2019. Or Tomlin's playoff record since 2009. Or Andy Reid's playoff record before 2019.
You seem to act like Carroll lost every game all by himself. Coaches can help players achieve their highest level of performance, but they do not play the game for them. You might know a little bit about football (I'm guessing from Madden), but you really seem to not understand "the game" and "the game" within professional football in particular....and you prove it more and more every time you post. If you did, then you would know that the number one factor influencing whether a team wins or loses is player execution. You can have the absolute best play calling and even the best coaches, but one busted play...one missed assignment...one injury to a key player...or one badly timed penalty can and often does change the direction of the game. The NFL is very competitive. This is proven EVERY SINGLE SEASON. At the start of each season, almost every fans says "this could be our year". At the beginning of the playoffs, most fans of 12 teams (now 14) thinks their team has a great chance of going to an even winning the SB. But in reality, less than half (44%) of the teams will make the playoffs and only 1 team (0.03%) will actually win the SB.
Based on what you post, you put out the impression that you think if a coach does not take their team to the playoffs each season or doesn't advance to later rounds in the playoffs then they are a failure and could never be successful in future playoffs or winning the SB. Almost as if you think they forgot everything they know about football after a couple of unsuccessful seasons.
I don't know where your hatred of PC came from. Were you a Husky fan with an ingrained hatred of PC from his USC days? Did he run over your dog? Date your ex? Pissed in your Wheaties? No matter, but the stats do not support your narrative. The opinion of other coaches do not support you narrative (PC is highly regarded by his peers). The opinions of most of the players that have played for him does not support your narrative. In fact there is really absolutely nothing that supports your narrative.
This team is playing well at this time. Who knows, they may explode and not win another game this season....or they may go on to win the SB. In any case, while PC will get credit or blame either way, it will be the players that win or lose any particular game.