General managers are always judged by their success in the draft. Former GM Rick Spielman had too many misses in the second half of his tenure. The best defensive players drafted by Spielman after his outstanding 2015 draft class were guys like Cameron Dantzler, Camryn Bynum, and Ifeadi Odenigbo. The trio, and many more, are solid backups or spot starters but not high-end players. Those misses are why the defense has struggled in the last few years.
That, in addition to some internal feuds, directly led to him leaving the organization after the 2021 season. The Vikings hired former Wall Street trader Kwesi Adofo-Mensah to replace him, but his first draft class was underwhelming.