Well, clearly the difficulty is happening to everyone except Ajax because they are currently having a blistering second half of the season campaigns. If I remember correctly, PSV was ahead with over 9 or double digits points but that gap is now super tiny.
If PSV doesn't sit up and Ajax continue this fine form, I won't be surprised if they later get to win the title.
I haven't followed this season as closely as the last few seasons, but Ajax have now won a total of 7 games in a row in the league, so they're already picking up a lot of points. Contrast that with PSV with three draws and one loss in their last 5 games. If Ajax's form continues, it will be difficult for PSV. Everyone else is already too far away for the title, in my opinion.