Heckingbottom was sacked by Leeds after less than four months in the role in the summer of 2018 and was replaced by Bielsa two weeks later.
The pair will go head-to-head in the Premier League's Yorkshire derby on Saturday when Heckingbottom returns to Elland Road as Sheffield United's caretaker manager.
Bielsa said: "The people who remain at the club and worked under him, they have a very good concept of the work he did here. I have only heard praise given for the time he was here.
"After the time it takes for players to mature and to be able to get the best of their abilities, they happen in different moments.
"What I value a lot is that a great portion of the players which are the base of the team, were here when he was around."
Heckingbottom, 43, who guided Barnsley to promotion to the Championship as caretaker boss in 2016, was appointed by the Blades until the end of the season following last month's departure of Chris Wilder.
The Blades, 14 points from safety and destined for a return to the Championship, lost Heckingbottom's first game in charge 5-0 at Leicester and in his second were knocked out of the FA Cup, losing 2-0 at Chelsea.
"They were two different games," Bielsa said. "Two games is not enough to observe major changes.
"It's very difficult that a coach can generate big changes in such a short space of time. Clearly, the game against Chelsea was a game of a very good level."
Leeds will reach the 40-point mark if they avoid defeat on Saturday, with a second season in the top flight all but assured.
Bielsa is waiting to learn whether midfielder Mateusz Klich has completed protocol and is available after recently testing positive for coronavirus, but captain Liam Cooper is available after illness.
It has been a frustrating season for both Spaniards due to injury and illness, while Rodrigo was compelled to issue a statement on Instagram this week strongly refuting claims he was unhappy at Elland Road.
The former Valencia forward has been unable to hit top form after a series of muscle strains, but Bielsa insisted he had nothing to prove.
"For me, Rodrigo has already shown how important he can be to Leeds. He has also justified with the conditions, the abilities he has, his transfer fee," Bielsa added.
"It's very difficult to obtain a player of his qualities in the scenario of football at the moment."