Fair to Martinez??? Two of his bullpen guys got traded for nothing because they complained about him. Rizzo made the deals but Martínez still shares the fault for why the pen is so bad.
This guy would be laughing his ass off if he was smart enough to figure out the situation, he got the job by promising a World Series, turned a 97 win team into an embarrassment, and he has the fan base making excuses for him so that he can flop again next year.
I'm not a fan of what I've seen from Davey, hasn't shown any improvement over the course of the season and I don't expect him to be better next year. That said, I don't necessarily blame him for the pen issues. 2-5 the starting rotation has been a complete mess this season and it's forced his hand to make pen decisions that would not have been necessary had certain starters stayed healthy and been able to last more than 4-5 innings per start. Obviously it's going to wear down a pen over the course of the season, and Dusty had the same issues before the Doolittle/Madson trade last year.
Davey wasn't hired because he promised a World Series, he was hired because Mark Lerner decided that anyone could manage this team to 95 wins and Davey was picked. Mark's paranoia about wanting his father to see a title has led to him playing amateur GM and making spontaneous, emotional decisions that go over Rizzo's head. Rizzo wanted Dusty back and instead was undermined. Mark sold the fans a bill of goods with the narrative of hiring a new school analytics type of manager because that was supposedly the trend in baseball, and if the Yankees and Red Sox could do it, why not the Nats as well, and Mark is learning the hard way. It's like a national baseball writer said a few years ago, when a manager gets fired the team usually hires a polar opposite personality and/or strategical approach just to change things up.
For all of the new school analytics talking points about Davey, Davey's mentor for the last decade is someone who has been notorious for wacky, off-the-wall decisions that go against the analytical norm. Blame Rizzo if you must, but it's not as if Rizzo had many options given the fact that the Lerners won't pay managers market value which limits the number of candidates who are even willing to come here. What they should have done was hire someone with experience but it wasn't going to happen because Mark was afraid of the backlash over booting 1800+ win Dusty to simply hire the same type of manager who had been previously fired and didn't have anywhere close to Dusty's win total. Davey has been put in this position by a paranoid owner, a bad philosophy and poor decision making, so in that regard I don't even blame him. He can't seem to hack it as a skipper whatsoever but the focus needs to be on who and what is responsible for putting him in the dugout to begin with.