Bullen, placed in temporary charge of the Owls last month, has boosted his prospects of landing the job on a full-time basis by guiding the club to back-to-back victories over Reading and Barnsley.
It is the third time Bullen has held the reins as caretaker boss since December 2017.
"I don't think any player would begrudge of him having his opportunity because he has done well in every chance that he has got," Lees told The Star.
"He obviously cares about the club and he has got a good relationship with the fans and players but it's not our decision.
"Players often get asked for their opinions but at the end of the day it is kind of irrelevant what we think. We just have to get on with it.
"What I do know is Bully's heart is in the right place and I am never not going to speak well of someone that gives everything and that is definitely what Bully does. He always gives it his all. He did that as a player and now as a manager.
"He is putting everything he can into it to make us better as a team."
Bullen has never hidden from the fact he wants the top job.
"I think I could do it going forward but I’m not going to put words in the mouth of anybody out there," said the Scot.
“I will just carry on doing what we have been doing and hopefully the results can do the talking."
His team will be looking to maintain their 100 per cent record when they travel to Millwall this weekend.
Lees said: "He [Bullen] deserves credit because he was put in a difficult situation again. It is never easy losing a manager, especially after we had done all the running and hard work in pre-season.
"You are getting ready and you think everything is going nicely and then suddenly the wind gets taken out of your sails a bit.
"It was not good timing at all and I think Bully has done really well to maintain the good feeling that we had as a group during pre-season so fair play to him for doing that.
"He has not done himself any harm."