Parthiv and the right length
The toughest thing to figure out for a fast bowler while bowling to Parthiv Patel is the right length. His stature allows him to go on the back foot quickly and, while he doesn't get close to the ball when it is full, he is adept at playing on the up on the front foot. In addition to that, he is comfortable opening the face of the bat to get singles. The ideal length is to make him drive but the lack of lateral movement off the pitch makes it a difficult to go fuller often. The seamer's pitch-map to Parthiv suggests that England's bowlers tried too many things without sticking to any one method for long enough.
Rahul and the impact of the IPL
KL Rahul's young Test career can be divided in two halves -- before and after the IPL. There has been a visible change in his approach after his successful season with RCB in 2016. Before, his strike rate in Tests was 47 but post-IPL it has shot up to 62 runs per hundred balls. The average number of balls he takes for a boundary stroke has also come down to 12 from 18. He started the second day in Chennai with two lofted shots against Liam Dawson and went on to reverse sweep Moeen Ali. While the world has moved back to more orthodox Test openers (David Warner is the only aberration), Rahul is taking a different path. In Tests, the technical aspect of batting overshadows the mental side of it but Rahul is highlighting the role mindset plays in the course you take. He hasn't made any technical changes to bat more fluently--it's just the mindset that has changed in last six months.
Rashid fits a season into a tour (almost)
The criticism of England's spinners has been about their accuracy, which imperative for penetration. While Indian pitches are spin-ready, the conditions still demand a spinner pound the same area ball after ball, over after over. Adil Rashid is England's most successful bowler in this series but his economy rate suggests that he hasn't been able to build enough pressure. Rashid has bowled 274.3 overs on England's Asian tour, spread over nine weeks - almost as many as the 293.2 he sent down for Yorkshire in the county season (although his involvement was limited by England call-ups). Bowling at the highest level demands takes a lot out of your body and, perhaps in part due to his increased white-ball role, it seems Rashid isn't used to this kind of workload.
Cook's problem of plenty
Ben Stokes didn't bowl a single over in the first session. He bowled four in the second session and picked up a wicket in those 24 balls. After tea, he bowled three more overs before disappearing until the end of play. Right through this series, Alastair Cook hasn't utilised his resources well. Having lots of options puts you in an enviable position but that can also cloud your decision-making with regards to using them judiciously.
Rahul v Spin
Most good players against spin are either very nimble on the feet or use the sweep shot well. Rarely do you see players who are quick to go down the pitch and also are equally comfortable in employing the sweep shot, and Rahul is from that rare breed. In fact, there are very few Indian batsmen who prefer the sweep to tackle spin, let alone playing the reverse-sweep. He is not just eager to dance down the pitch but also has a fair amount of control on all variations of the sweep shot. Rahul's overriding thought while facing spinners is to look for scoring opportunities, even if that meant taking a few risks.