Worst finish was 7th the year after the last title and the year with Moyes.
Since 2013, we have finished:
7th: 1 time
6th: 3 times
5th: 1 time
4th: 1 time
3rd: 2 times
2nd: 2 times
(Note we finished as low as 6th as recently as 2022 so it's not like we're far removed from one of our worst finishes ever)
We've finished outside the top 4 as many times as we've finished inside the top 4. This year will make it more times outside than inside. Our average position has been 4.4. In the 10 years from 2004 to 2013 (which mostly aligns with when the Glazers took control of the club), our average position was 1.7.
At that rate of decay, it's not inconceivable...and I would say it's highly likely...that the average position for the next 10 years (so 2033) would be about 7th or so. At a minimum.
But I would argue that once you slip out of the top 4 on a regular basis, the drop down the table accelerates because you don't have CL money and even though the Glazers may think their club's commercial power is infinite, it's not. We're already seeing that it's not. The club is BROKE. Add in the fact there are a lot more clubs with money, stadiums, and organizations that can compete with United...a lot more than there were 20 years ago, and I definitely think a mid table club at best who is occasionally closer to relegation than it would like is more likely in 2030 than a championship.