I got fooled by Garrett in 2014 and 2016. I was ready for him to be gone before 2014 when the best he had done was 8-8 (for three straight years), then came the 12-4 season in 2014 and I thought I might be wrong about him. It was fool's gold, though, as was 13-3 in 2016.
So now, my expectations are progress each year, culminated by a Super Bowl appearance by Year 5 or move on. I did some research that I posted in a thread concerning coaches that showed in this era especially that Super Bowl coaches get there within five years.
McCarthy had a rough first year because of injuries (especially to his starting QB), bounced back to make the playoffs and then showed he could repeat success without just relying on a weaker schedule (like Garrett had) and make it past the first round. I would love to win the Super Bowl this year, but I feel like showing he can get the team to the NFC championship would be enough progress to earn him one more year.