You are only talking into account offense. Danny Green is one of the best perimeter defenders in the league, while Burks is subpar.
I listened to a Grantland podcast earlier this year where Zach Lowe talked with JJ Redick. Redick said that the combination of Green and Leonard was definitely the toughest defensively in the league. He talked about how Leonard got all the press and recognition for his D, whereas Green was very tough, but wasn't as recognized for it.
Green has said before that he would be fine coming off the bench. He's also an elite 3 and D guy, which would be a perfect fit for the Jazz.