He did in many cases
Mitch had been ignoring blue slips for appeals court judges, but complying for lower-level district judges.
Right now, the appeals vacancies have almost all been filled, with just one vacancy left. But there are 72 district court vacancies, with another 3 pending.
https://www.uscourts.gov/judges-judgeships/judicial-vacancies
Mitch has done a good job, with 107 vacancies filled in the last 12 months.