It wasn't a particularly fast innings, nor a particularly slow one. It was a little faster than the average 50 in T20 internationals. (The median strike rate for 50's by openers in T20 internationals is 151.3, Guptill scored at 170.6. The upper quartile is 171.4, so Guptill's innings is in the second quartile). Here's a graph showing his innings compared to all fifties in T20I's scored by openers.

We can see that Guptill's innings doesn't really stand out from the pack. So why was it so interesting?

I think it was interesting because of how and when the runs were scored, rather than how many or how fast.

First, let's look at the progression throughout the innings:

There are a couple of things that I need to explain here. Firstly the weighted strike rate is weighted to put more value on recent deliveries that older ones. For the starting value I used his career strike rate.

Secondly I've added in a logarithmic trend line onto the runs scored. This is possibly the first time I've seen a limited overs innings that fits a logarithmic trend so well. Normally batsmen accelerate, rather than decelerate.

And that's the interesting thing about this innings. Guptill seems to have started in 5th gear and then started shifting down, rather than up.

After 10 balls, he had 31 runs, with a strike rate of 310 and a weighted strike rate of 366.7. At that rate he was almost on track to equal his T20 record for the fastest 50 in NZ of 15 balls. But then things stalled.

My question was, "what happened?"

I had 4 different theories:

- The powerplay - Did he score more freely with the field up, but struggle with it back?
- The introduction of spin - Did he struggle against spin?
- Different bowlers - Was it just that there were different bowlers bowling?
- Change in bowling plan - Did the bowlers pitch the ball in different places?

#### 1. Power play

First step was to compare the strike rates during the power play and after the power play.

During the power play he faced 18 balls and scored 36 runs (strike rate of 200). After the power play he faced 16 balls and scored 22 runs (strike rate of 137.5). This looks like the explanation. He scored 45.5% faster during the power play overs than outside. But this blog is about digging a little deeper.

Let's break it down by bowler type.

He hit 36 off 15 from the pace bowlers during the power play (strike rate 240) and 14 off 8 outside (strike rate 175). These are not so different. He did 37% better during the power play than after it.

Against spin he scored 1 off 5 balls during the power play (strike rate 20) and 8 off 8 outside it (strike rate 100). He scored 5 times faster outside the power play than inside it!

The difference in his scoring rates may just be because he faced more spin after the power play than during it.

#### 2. Spin

That leads neatly onto looking at the introduction of spin.

He scored 49 off 21 from the quick bowlers (s/r 233.3) and 9 off 13 from the spin bowlers (s/r 69.2). He scored roughly 3.4 times faster off the quick bowlers than off the spinners.

Now this doesn't necessarily indicate a weakness against spin. It seemed that the strategy of the partnership was that Guptill tried to hit boundaries off the quick bowlers, and rotate the strike off the spinners, while Williamson was trying to do the opposite. They each had their own area of strength, and they played to it.

We can see that in a breakdown of how he scored his runs against each type of bowler:

He hit just under 40% of the deliveries that he faced to or over the boundary. There were a couple of lucky shots in those 8 boundaries, but even if you discount those, the difference is still marked.

Interestingly, he had 5 dot balls, 7 singles and 1 two against both the spinners and the quick bowlers. The difference was that he wasn't hitting the boundaries in between.

But, once we look at what happened in the context of the innings, something else interesting pops up.

Guptill even started scoring slower against the quick bowlers after the introduction of spin. It seems like the change in mindset of rotating the strike for Williamson may have impacted his batting in subsequent overs.

Here's another way of looking at it:

Before Jayasuriya came on to bowl, Guptill was scoring almost 3 times faster than he did after that point. (For the strike rates in this graph I've actually used the gradients of the lines, they are not his actual strike rates,but rather the trend of how he was scoring)

#### 3. Different bowlers.

Fortunately, he faced each quick bowler before and after the introduction of spin. This means that we have something to compare.

Off Perera his strike rate before spin was 367, and after spin it was 220. Off Lakmal his strike rate before spin was 233 and afterwards was 100. Off Kulasekara his strike rate was 350 before spin and 150 afterwards.

Which bowlers he faced wasn't as big a factor as the introduction of spin.

#### 4. Bowling plans

The next thing I did was go through ball-by-ball and see where the ball was directed. Was there a pattern here?There were no deliveries that pitched outside leg. I broke the others down into "pitched outside off" or "pitched on the stumps."

Guptill scored 50 runs off the 22 deliveries that pitched outside off, as opposed to only scoring 8 off the 12 deliveries that were bowled straighter. This is a significant difference. He scored almost 3.5 times more from the deliveries that were a bit wider. This also goes against the conventional wisdom that says that he is so strong at driving down the ground and playing the pull shot, that bowling on the stumps isn't such a good idea against Guptill.

And this is part of what happened. Almost all the deliveries in the first 3 overs were outside off stump. Almost all of them were dealt to. In his second spell Lakmal bowled all but one of his deliveries to Guptill on the stumps, as opposed to only one in his first spell. Perera also changed his line. The difference was that he bowled a full toss that was hit for 4 and one that was only just outside off that Guptill backed away from and hit over cover for 6.

### Conclusion

So which of the factors was it? I think a bit of all. Guptill's mindset seemed to change after the spinners came on, but also the bowlers change their line to him. He struggled to score off the spinners (although neither of them really had him in any trouble) and he had 6 deliveries fielded on the boundary after the power play, that would have possibly been 4's if the fielding restrictions were still in play.

The fascinating thing will be to see if the same pattern occurs at Eden Park for game 2 (if the rain relents enough to allow any play at all). Will Guptill go into his shell once the spinners come on again? Will the Sri Lankans risk bowling straighter to him with Eden Park's short straight boundaries?

Innings like this throw up more questions than they answer. Hopefully Sunday will give us some more questions to ponder.

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