Leading thanks to a 20th-minute header from Andraz Sporar - his first goal at the Riverside - Boro missed a string of chances to make the game safe on a night when the margin of victory should have been a lot more comfortable.
Duncan Watmore produced a contender for miss of the season just before the hour mark, ballooning the ball over an empty net with it left to the impressive Crooks to seal the three points three minutes from time with a header.
Warnock, whose side have chalked up back-to-back wins for the first time in 2021-22, said: "We were a little bit apprehensive in the first five minutes and they had a good chance to go one up, but after that I thought we got right on the front foot.
"They put me through the mill and we should have been comfortable."
On Watmore's miss, he added: "He did slip in fairness. But I said that when he slipped, he should have gone on his knee and headed it in!
"But listen, he worked his socks off and both the strikers did and I have nothing but praise for them. You get praise when you score and (then) disappointment. But the main thing is that we won the game and it does not make his miss as bad as it would have done."
It was a night when all the home players contributed in a sound team performance, with Warnock reserving praise for veteran duo Lee Peltier and Sol Bamba, alongside man-of-the-match Crooks.
Warnock added: "The two lads who I never expected to be in the team in Peltier and Bamba were outstanding. I don't think I have seen Peltier play a better game for years than he did tonight. He's an unsung hero really and his determination..
"With both of them in the dressing room at half-time, they did my job for me, really. That is what you need, characters like that and I was delighted for them both."
And on Crooks's contribution, he continued: "I said to him before: 'If you get booked, you are in training morning, afternoon and night' for the next week or ten days, so it is up to you.
"Then at the end, I thought I cannot risk him and I subbed him quickly after the second goal went in. He has been instrumental and he helps Martin (Payero) all the time in becoming more accustomed to his role at this level and he has so much energy that it rubs off on you."