It is believed that comebacks are a lot tougher than debuts. For the latter, while there's anticipation about seeing a new player for the first time, when someone is making it back into the side, there's only expectation from them.
As a player, you don't want to think about how and why things went pear-shaped last time around; that will only add to the pressure. Unfortunately, try as you might to keep them away, those memories find ways to make an appearance. And if your first outing on return doesn't live up to expectations, the pressure of walking out the next time is immense. You're trying to tighten your fist as you feel sand slipping out of it fast.
His opportunity had arisen because KL Rahul and Rohit Sharma were unavailable, which made you wonder what the returns for a good performance by him would be. The best-case scenario, in which he would cement his place in the squad, also hinged on how Shubman Gill performed; Agarwal was fourth in the pecking order. A good performance should not result in a no-win situation, but this one was. Of course, in the worst case, he would be dropped from the side if he didn't fire in the second Test too.
Agarwal started cautiously against the New Zealand fast bowlers and looked decisive with his foot movement and shot selection. As soon as the spinners arrived, he switched on his A game. He is one of the finest Indian players of spin, with as much confidence in his defensive technique as he has competence in strokeplay.
The foundation of his game against spin is the ability to stretch fully when the ball is full, and to go deep inside the crease for short-pitched deliveries. He is quick to dance down the pitch but not reckless in his shot selection when he does. In fact, it seems like he steps out to try to get as close to the ball as possible, then playing along the ground.
With such a tactic, your weight is always going forward, which is ideal. For Agarwal, stepping out doesn't equal committing to playing an aerial shot, so he has plenty of choices after he steps out. A lot of players start their forward movement with the intent to go big, and when they get it right, they do manage big shots, but when they end up not as close to the ball as intended, they sky it, because the weight starts going backwards. Agarwal steps out the way it should be done: you stay low, with your weight going forward all the time.
It's not just about technique but intent and confidence against certain types of bowlers. If you are unsure about your defence, you look to attack at the first opportune moment, and if that doesn't arrive quickly, you end up manufacturing shots. That's where Agarwal is different: he is comfortable defending ball after ball, which in turn allows him to pick and choose the deliveries he wants to target.
The second part of Agarwal's success in attacking against spin is his ability to pick areas in the field that are rarely manned in the longer format. Not that he can't clear the fence - he does it regularly in T20 - but in Test cricket it's important to pick areas where even a half-decent connection is enough to fetch a boundary. His inside-out shot over cover against left-arm spinners and over mid-off to offspinners are two such shots that target optimal areas in the field.
In Tests, it takes a lot of beating for a left-arm spinner and an offspinner to push those two fielders back to the fence. When that happened, as it did in Mumbai, it allowed Agarwal to move swiftly deeper into his innings.
In addition to the lofted shots while stepping out, he was equally adept at using the depth of the crease to punish bowlers either side of the pitch if they pulled their lengths back too much in anticipation of him dancing down the track. And while he might not have used the sweep in Mumbai, he has that option covered too.
In a nutshell, he has everything it takes to be a superb player against spin, which will always make him a successful player at home. If he continues to develop his game against pace, he will continue to present himself as a tempting option. Considering his prowess against spinners, India might start viewing him as an option for the middle order if a spot doesn't open up at the top.