Giacomo Calò put the hosts ahead in the ninth minute after a Sassuolo error in possession. Domenico Berardi levelled six minutes later, finishing after a forward pass from Bakola opened up the defence.
Raimondo restored the lead in the 26th minute when goalkeeper Arijanet Muric failed to deal with a cross. The striker pounced again four minutes later, capitalising on another Muric error to make it 3-1.
Sassuolo replied when Kristian Thorstvedt finished from Sebastiano Esposito’s pass in the 37th minute. But Frosinone had the final word after the break: Raimondo completed his treble in the 57th minute, following Muric’s save from Farès Ghedjemis’ header.
The win lifted Massimiliano Alvini’s side to 13 points and fourth place, while Sassuolo remained on eight. Raimondo moved to seven league goals in seven games and became the first Frosinone player to score a Serie A hat-trick.
Alvini praised his team’s second-half performance.
“I think we managed the whole second half very well. We were up against a strong team with good players in one-on-one situations. This is an important victory, of great value, and that is the team’s merit.”
Alvini stressed that survival remained the target.
“There is important work behind this, from the staff, from me and from the club. The path we have to follow is clear. We must not make a drama out of what happened after Napoli, just as we must not get carried away now. We want to stay up and build an even stronger foundation.”
Alvini credited sporting director Renzo Castagnini with bringing Raimondo to the club, but warned the striker against complacency.
“He is improving, and I am happy for Italian football, but he has to keep working and have the ambition to improve, not presumption.”
Sassuolo coach Alberto Aquilani felt his side had been beaten by Frosinone’s greater intensity.
“Frosinone had something extra in temperament and in their desire to win the loose balls,” he said. “Errors shape the course of a game, but we were lightweight today.”
Aquilani refused to blame Muric alone, despite his costly errors.
“We did not lose because of him,” he said, while demanding greater conviction in attack. “We can look good, but that does not get you very far. We have to be more ruthless in front of goal.”