- Bats Right, Throws Right
Casseri debuted in 1995 with Caserta. The teenager went 7-8 with a 6.33 ERA, walking 102 in 101 innings. He allowed a .256 average and .350 slugging but a .403 OBP. In 1996, he was 2-5 with a save and a 8.41 ERA, walking 33 in 46 innings. Moving to Grosseto in 1997, he improved to 7-3 with a save and a 4.96 ERA. In 1998, he was 11-2 despite a 6.40 ERA and .301 opponent average; he tied Diego Ricci for the league lead in wins. The next year, he had his best season overall at 10-2, 3.69. He walked 65 in 97 1/3 innings but only allowed three home runs. He was two wins shy of league co-leaders Tom Urbani (a former major leaguer) and Battista Perri.
Casseri was with the Italian squad in 1999. He retired all six batters he faced in the 1999 European Championship (when Italy won the Silver Medal). In the 1999 Intercontinental Cup, he allowed six walks, three hits, a hit batsman and 7 runs in four innings. He joined Nettuno in 2000 and was used solely as a reliever; one of his bullpen mates was Ricci. That meant that Nettuno had two relief pitchers who had shared the league lead in wins just two years prior. Massimo struggled in that role at 3-2, 5.45 with a .314 opponent average. He was not kept on the Italian team for the 2000 Olympics after having been with them in 1999. In the 2000 Italian finals, he was torched for five hits and three runs in 1 2/3 IP. Nettuno fell to Rimini.
Massimo rejoined his original Caserta club in 2001, going 2-1 with a save, 7.50 ERA and .368/.444/.443 opponent line. In 2002, he was with Anzio, posting a 3-3, 5.72 record, while opponents batted .323/.390/.398. He was 3-9 with a 7.04 ERA, while he allowed a .327/.407/.448 line. He tied for third in the league in losses while allowing the most runs (87) and earned runs (72). His next stop was with T&A San Marino, his fifth team, where he spent his last four seasons.
In 2004, Casseri was 3-4 with a 4.74 ERA for San Marino. He went 6-3 with a save and a 2.97 ERA in 2005, the best ERA of his career. In the finals, he was 0-1 with 9 runs, 8 hits and 7 walks in only 4 1/3 IP, as San Marino fell to Bologna. During 2006, the veteran was 3-5 with a 4.66 ERA; opponents hit .305/.412/.369. In his last season, still only 29 years old, he gave up six runs in 3 2/3 IP.
Overall, Casseri was 61-49 with four saves and a 5.58 ERA for his career. He allowed a .277/.375/.404 batting line.