Under Maifredi, our record in Serie A was 34 games, which included 13 wins, 11 draws, 10 losses, and a goal difference of +13. We also reached the Cup Winner's Cup semis that season, only losing to Farcelona. That was the Golden Era of Serie A, so the competition was intense.
Ferrara only had 30 games with 15 wins for a 50% win ratio.
Zaccheroni was only on our bench for 21 games, so the sample size is way too small.
Del Neri's record was 38 games, 15 wins, 13 draws, and 10 losses, with a goal difference of +10.
Trapattoni's 2nd stint was comprised of 142 games, including 74 wins, 44 draws, and 24 losses for a goal difference of +112. In his 3 seasons back, we finished 2nd twice and won the UEFA Cup in 93. Serie A was ultra competitive back then, especially with the Dutch trio at Milan.
Under Ancelotti, we played 114 games, with more than half of them (63) wins, another 33 draws, and 18 losses for a 55.26% win percentage. We only missed out on the Serie A title in both seasons on the last day, missing out in 2000 and 2001 by 1 and 2 points respectively. Ancelotti was not a failure, but the standards were so high back then, so he got canned.
What do all these coaches have in common, Trap aside? They were all fired.
Perspective is imporant - if we look at Failegri's overall body of work, it undermines the work he accomplished/achieved here in his 1st stint. If we look at his first spell independently, it's clear he is a top 3 Juventus coach. If we only look at his 2nd tenure here, it's evident, objectively speaking, that he is one of the worst, if not the worst coach in JJ history.