Sheridan, who played for Leeds from 1982 until 1989, has been impressed with how hard the players are working this season.
The former Republic of Ireland international midfielder told BBC Radio Leeds: “I am watching games, and the work ethic of the team is unbelievable.”
Leeds are having a great season in the Championship and are very much in the running for automatic promotion to the Premier League.
The West Yorkshire outfit are at the top of the league table at the moment with 30 points from 16 matches.
The Leeds players are working hard under Bielsa, as typified by almost the entire team back-tracking to dispossess John Windass during the win against Wigan Athletic in the Championship last weekend.
Leeds maintain their high-press and intensity throughout the 90 minutes, and the Elland Road faithful are loving it at the moment.
Some may have concerns whether the Whites will be able to maintain their current form and intensity for the rest of the season, but all the signs are very positive for the West Yorkshire outfit.