Root piled the runs on the tourists at The Oval earlier today to leave England on 385-7 heading into tomorrow.
"He's played very positively," Ballance is quoted as saying by BT Sport. "He was patient and got used to the pace of the wicket and then looked to score - and that's what he's done very well this summer.
"He's obviously got that ability [to change gear in an innings], and today he had a chance to put pressure back on India and did that very well and scored very quickly.
"To watch how he's handled it after a tough tour of Australia and come back this summer and scored big, big runs - when the team needed them - just shows he's a quality player."
Root made his England Test debut in 2012.