Reja enjoyed a winning start in his second spell in charge of Lazio on Monday as his team prevailed 1-0 over Inter Milan and the Romans will be looking for a similar display when they visit Bologna on Saturday.
Lazio parted with Vladimir Petkovic last weekend and handed the reins to Reja, who guided them to a fourth-placed finish in the 2011-12 campaign before deciding to leave the club.
"With Reja, the team seems to play with more fluidity, we have more clear ideas from a tactical standpoint," Hernanes said. "The (coaching) change has done us good.
"Each coach has his own philosophy and now we are playing a different style of football.
"The win against Inter was extremely important for us.
"It has given us a big boost in confidence and now we hope we can start improving our results away from home."
Lazio have yet to win on the road this season and are 10th in the standings.
Rivals Bologna made a coaching change this week with Davide Ballardini replacing sacked Stefano Pioli following Monday's 2-0 defeat at Catania, Bologna's third loss in four league games.
Ballardini, who has signed a contract until the end of the season with the Rossoblu club, has plenty of experience in Serie A having coached Cagliari, Palermo, Lazio and Genoa.
However, the veteran coach faces a big task to turn things around at Bologna with the team having won just three of their 18 games this season.
The Rossoblu are 17th in the standings, one point and one place clear of the relegation zone.
The hosts will be without defender Andrea Mantovani and midfielder Francesco Della Roca, both serving a one-match ban.
However, they will be bolstered by the return of playmaker Alessandro Diamanti from suspension.
Diamanti is alongside Panagiotis Kone the team's top scorer with four goals netted.
Lazio will be without suspended defender Stefan Radu.