With 21 points and 15 matches left, I look at it like this: if we divide those 15 matches into 3 5-match sections, can we get 6 points from each of those sections?
Here's what that would look like:
#1
View attachment 204845
#2
View attachment 204846
#3
View attachment 204847
If we get 6 points out of the 15 available in each section, we finish on 39 points, which would almost certainly be enough.
Before anyone says that can't happen, do remember that we just got 6 points from 9 that most thought didn't look likely either (Arsenal - Liverpool - Leeds).
We might not even need that much. 4 more wins + 4 draws gets us to 37 points, which could still be enough in many scenarios.