2. Failure to bolster WR room after injuries
Three wide receivers all ended up not suiting up for the team in 2023 due to varying reasons. All of Tim Patrick, KJ Hamler, and Jalen Virgil each came with promise into 2023. The Broncos were likely hoping all three were going to contribute to some degree. Both Patrick and Virgil went down with season-ending injuries, and Hamler's scary medical issue eventually led the Broncos to end the experiment with the former second-round pick.
Well, in response to all three not being on the field for 2023, the Denver Broncos did absolutely nothing. It's clear that Courtland Sutton was the only consistent WR on the roster, and even he was a bit inconsistent at times. Had the Broncos looked to who was still out there in the free agency market over last summer, they may have been able to fill out the rest of the WR depth chart.
3. Letting Ronald Darby go
I know this one might seem a bit silly, but the Denver Broncos cutting Ronald Darby and not bringing him back was an insane move that blew up in their faces. Darby tore his ACL in Week 5 of the 2022 NFL Season. He played in just 16 of 34 possible games with the Broncos. Denver cut him to save some cap space, and Darby even latched on with the Baltimore Ravens, playing 16 games with them in 2023 and racking up seven passes defended.
Darby is very good in coverage, and man, the Denver Broncos CB2 spot in 2023 got manhandled. Damarri Mathis was a disaster, and he was eventually replaced by Fabian Moreau. Moreau seemed fine initially, but I think he had a rough stretch to end the season. I have to wonder just how much bet the secondary would have played if Darby was on the team in 2023.
Perhaps the Broncos don't get torched by various QBs during the first chunk of the season, and you never know, that could have led to a couple more wins.