This is more than personnel, and sending guys up/down to Rochester. Bullpen isn't just last in ERA, it surpasses the rest of MLB in BB/9, P/IP and plunking batters. This is poor coaching. Hickey is Davey's friend, and is a useless fool who makes way too many mound visits that usually end up with the wheels coming off, and who thinks staying in the zone consistently is just "analytics stuff". As long as the org refuses to address this, we'll continue to get excited when they go 4 innings in a row without giving up an earned run, only to blow up the next day. This is fixable, but the solution depends on changing org politics, so unfortunately isn't likely to happen.
This is ... poor analysis, at best and is pretty encumbered by emotion and bias.
First off, Hickey became the pitching coach in 2021. From 2021 through 2024, the Nationals' bullpen was 14th in BB/9. Not bad, but certainly not good. It was 17th in HBP over the same time period. In 2024, the Nats bullpen was 18th in P/IP. 2023 they were 10th. 2022, they were 13th. 2021, 1st. 12th in 2020. And 2nd in 2019. The issues you are bringing up are much more prevalent this year compared to previous years, both during Hickey's tenure and before it.
This seems much more related to the personnel we have in the bullpen. Last year, before the deadline, we had a healthy Harvey, Dylan Floro having a bounceback campaign, Finnegan having an all start season, and Derek Law being beast in the pen. In the first half of 2024, the Nationals bullpen had the 7th best BB/9 rate and was tied with Boston for the 3rd fewest HBP. I can't find a way to split out P/IP to get reliever specific numbers, but overall, Nats pitching, overall, was 14th in P/IP in the first half of 2024.
The talent disparity in the bullpen cannot be ignored. The 2024 bullpen had all star Kyle Finnegan, Hunter Harvey having a good season, Dylan Floro posting a 2.06 ERA, and Derek Law was a beast. Robert Garcia, while he had a high ERA, didn't seem to have control issues. Only Finnegan had a BB/9 over 3. Contrast that with this season's "core" bullpen that includes Jorge Lopez (who is actually having a his best control in several seasons), Lucas Sims (who has always had control issues), and Poche (who imploded this season). We're talking about a dramatic drop off in talent and ability from one season to the next. On top of that, we have a several young/developing pitchers in our current pen. Jackson Rutledge has never been particularly adept at throwing strikes (hence why is a reliever). Cole Henry is pitching post-TOC, which brings a wealth of issues and concerns. Then you have Ribalta and Bryzkcy who are getting their first real tastes of MLB pitching, so this is a learning experience for them.
Now, I think Hickey and the coaching staff deserve some blame. Ferrer is regressing and no one can explain why. Poche looked awful when, historically, he's been pretty okay. I'm not particularly impressed with Salazar, and somehow Sims is even worse than before he got here. Then again, outside of Ferrer, none of these guys were particularly sought after in the offseason and were very cheap.
I think it's pretty unfair to lay this solely at the feet of Hickey. And unless you have some sort of definitive proof that Hickey thinks "staying in the zone consistently" is just "analytics stuff," then I'm inclined to dismiss your characterization as simply your own bias. I defy you to find a pitching coach that doesn't preach filling up the zone with strikes. If anything, "just throw strikes" and "fill up the zone" would be the opposite of analytics, which would preach location in combination with pitch spin and shape.
I think it's more apt to lay majority of the blame for this bullpen on Mike Rizzo and ownership. This team has struggled to develop pitching in the past. Some of that has gotten better, but it's pretty clear that it's not great right now. It's also pretty clear that Rizzo did not have a particularly large budget this offseason, and had to buy the bounceback candidates, which are performing poorly. Then you couple that with injuries to Law and Ribalta, combined with young relievers looking to develop at the MLB level, and we have a perfect storm for a terrible bullpen. And I just don't think it's particularly justified to say that the problem is simply poor coaching. No matter how great your coaches are, they are dependent on their system to produce major league talent. That simply isn't happening here in DC. At least not where the bullpen is concerned.