The data was taken from Il Napolista. Sarri's first season at Napoli and his second season in Serie A.
1. Wins (20 team league)
Mazzarri (2012-13): 23
Benitez (2013-14): 23
Sarri: 25
2. Home wins
Mazzarri (2012-13): 14
Sarri: 16
3. Fewer home defeats
Sansone (1946-47): 1
Mazzarri (2012-13): 1
Sarri: 0
4. Greater number of consecutive wins
Sarri: 8
Previous record: Bianchi (1987/88): 7
5. Most points scored in a season
Mazzarri (2012-13): 78
Benitez (2013-14): 78 (63 last season)
Sarri: 82
6. Greater number of points obtained at home in a season (3 point - 20 team)
Mazzarri (2012-13): 46 points
Sarri: 51
7. Greater number of goals scored in the league: (20 teams)
Benitez (2013-14): 77
Sarri: 80
8. Fewest goals conceded in the league (20 teams)
Mazzarri (2012-13): 36
Sarri: 32
9. Total goals scored in a season.
Benitez (2013-14 and 2014/15): 104 out of 59 meetings
Sarri: 106 out of 48 meetings
10. Total goals scored at Group Stage of Europa League
Napoli/Sarri : 22 goals (100% win rate)
So 10 records broken in his first year, and 11 if you include the collective for Higuain's 36.
Best Italian coach in Serie A ???