Because maybe Reirden isn't the problem like many here want him to be, he might be one but it falls on the head coach, even when Reirden was with the Caps as Head Coach, his powerplay tanked with Forsythe and his team was ousted early twice and he was out, yet he still put up 40+ wins both times (won division twice). The funniest shit is that Reirden won a cup as an Assistant before taking over as head coach, he wins the division twice, loses in the 1st round twice and is fired, meanwhile in those 2yrs, Sullivan is out in the 1st round and then the Qualifying Round, which is to me his first playoffs miss. I mean here's a good example of the issues and what the powerplay has been with the other Assistant before Todd.
Mark Recchi's tenure running the powerplay per season:
2017-18 - Ranked 1st
2018-19 - Ranked 5th
2019-20 - Ranked 16th
Todd Reirden's tenure running the powerplay per season:
2020-21 - Ranked 4th
2021-22 - Ranked 19th
2022-23 - Ranked 14th
2023-24 - Currently 27th
From 2016-17 to 2018-19, the Pens ranked 4th (Tocchet), 1st (Recchi), and 5th (Recchi). That was their best stretch. Reirden came on board the first stint in 2010-11, Pens were ranked 25th that year, then 5th, 2nd, and 1st before he moved on to the Caps, then came the dreadful MJ era - 2014-15 they dropped to 10th, 16th, and 4th with Tocchet at the helm. The funny thing is in his first stint - he did amazing, that first year was rough, but then 5th, 2nd, and 1st? Yeah you can't ignore that. Also you can't ignore the Caps powerplay that he ran as well.
With the Capitals - their situation was weird, if you looked at who ran their powerplay, you'd read that Blane Forsythe did from 2012-2023, but during Reirden's tenure as Assistant he also coached the Defense and the Powerplay as well, as head coach, Blaine took over sole duties again. In the time Reirden was there as Assistant - They had some pretty solid years on the powerplay as well as getting better defensively (1st, 5th, 3rd, and 7th were the PP ranks for Reirden's time - then when he took HC, Blaine had them do 12th, 17th, 3rd, 23rd, and 16th, now he's with the Coyotes where they jumped from 24th to 11th). His defensive work though - they went from 21st the year before him to - 7th, 1st, 1st, then 16th.
It's easy to shit on Reirden, but the blame to me falls on Mike Sullivan. To be fair, I would probably fire Sullivan & Reirden together and name Vellucci the interim head coach.