Mahmood has quietly built up an impressive coaching career, with international experience with Pakistan burnished by stints in the Pakistan Super League - most recently as head coach at Islamabad United. As an interim assistant coach at Surrey, he has taken on Overton as a personal project and early results, after a little technical tweaking, have been spectacular.
"The first thing we did with him was to reduce his run-up," Mahmood says. "We reduced it from 24 yards or so that it was before to around 18 now. He was losing momentum when he was running in for those last strides to the popping crease, where you actually have to build that momentum up."
Because of that loss in momentum, Mahmood explains, he wasn't following through towards his target properly. "When you drive your hip through in the action, you transfer weight and bring your hip forward, for the follow-through. He was stopping a little but if you watch now, he gets closer to the batsman. He is taller at the crease now."
Mahmood is meticulous when it comes to thinking through bowling actions, though he's careful to not tinker too much. His phone is a video treasure trove of bowlers and bowling actions from his work around the world; little tips that he's given them, minor tweaks he's made, hours he's spent just watching and logging.
He identified Overton's run-up as a prime cause for the inconsistency in his release and action, which would result in him often straying down legside. But pre-season work brought some immediate results. After shortening the run-up, Mahmood asked Overton to note how many balls he bowls down the legside. Overton bowled to Hashim Amla in the nets one day for half an hour and Mahmood remembers only two balls that Amla could play through the legside. Amla was impressed and wondered whether Overton could sustain that consistency.
"Now you can see, it's half a season gone and he's been sustaining it," Mahmood said. "Because of his pace that inconsistency can creep in. At that pace, a good day can be a great day, but a bad day a very poor one. If you're slightly off line at that pace, you go for runs. Jamie's getting that consistency now. He's still a work in progress. That will keep going. But this season I think people have seen the best of him."
"I spoke to him about his batting," he says. "I said you remind me of myself, you have exactly the role I used to have. To help build an innings lower down in the order. I said to him this is the role. With that batting this guy can be one of the best allrounders in the world.
"I really haven't done that much with him. Jamie Overton is special. He is a diamond. All we've done is to cut and polish him a little."