Just for references sake, glancing at Mowbray's time at Coventry (purely looking at the record, no idea about context actual context, which I gather was generally less than ideal, etc.):
Joined in March 2015 with Coventry in 20th place. Went 5-4-5 the rest of the year (a pace that would've put them T11th over the course of the year), and they finished 17th.
2015-16, Coventry had a very strong first half, being in 1st place as late as the end of November with a record of 11-6-3. However, they had a pretty miserable run-in, going 8-6-12 to finish the year in 11th.
2016-17, pretty awful with Mowbray resigning after starting the year 0-6-4 and dead last. May not entirely have been his fault given the apparent turmoil at Coventry, and while Coventry had a brief respite after he left, they've since had 7- and 5-game losing streaks, and are 9 points from safety (though they now have Yakubu who will surely save them).
Always struck me as a bit odd that draws are often effectively ignored in evaluating manager's this way (I get it, who enjoys settling for draws and they don't exactly get you cups/promoted/etc). 40% tends to strike me as pretty 'typical' number for a managers that manage to stick around football, albeit not with the same team...