50% more wins is not reasonable by any metric
Why not? The lower the win total the easier a high % increase is. I'll give you some Jim Calhoun stats on year over year win increases (including Northeastern) and this is just one coach:
1979 to 80 13-13 to 19-8 46%
1983 to 84 13-15 to 27-5 108%
1987 to 88 9-19 to 20-14 122%
1993 to 94 15-13 to 29-5 93%
1997 to 98 18-15 to 32-5 78%
2010 to 11 18-16 to 32-9 78%
So one coach did it (or close to it and in come cases 100% more wins) 6 times at 2 different schools. Going up 50% in wins is hardly unreasonable when given the low previous year win base requires only 7 more wins to get increase to 50%. Jim was so good he even did it following 18 win seasons twice, the last time in the Kemba year.
Want to really know how easy/often a 50% increase happens, even KEVIN OLLIE did it off of a 20 win season:
2013 to 14 20-10 to 32-8 60%
And we all know how bad a coach Kevin Ollie was.