Very interesting topic thus far and love the fact that people are talking and discussing bat shapes and how it affects the bats performance.
For me it is quite simple and Chris did mention it a few times in the video, only reason to concave is to reduce weight whilst still maintaining a visually big bat. There is absolutely no evidence; especially in the paper that he refers too that concaving increases the structural integrity. The reference to a bridge did make me laugh a little. Bridges and Bats, the only thing that they have in common is the B.... One is a static load whilst the other is a dynamic impact. I'm afraid the majority of the video is marketing and marketing alone, which is done quite a lot by the big boys.......
I think all the comments have merit in this thread- the first is about shape and optimising that shape to get the maximum performance and the other is about the willow, and maximising the material to get maximum performance.
What I would do is this;
Calculate the optimum bat shape with a homogenous material - that will take the natural variation in material out of the equation and we could say that design A is superior (CoR) to design B for a given impact position, given a uniform weight and swing speed.
The next question I would ask is that what makes design A superior, and would design A still be superior to B, if the ball impacted in a different position. I think the answer to that would be no, and therefore there is no optimum bat shape, and each player (both amateur and Professional) would have an optimum bat shape. This is where the 1271 shape comes into its own as it has a very large middle, and excellent CoR all the way up the blade. However this is not the Eureka bat shape as it would be too heavy using the average density for the majority of cricket players. Therefore you would need to calculate each person’s optimum bat design to get the most out of the cleft and have the facility to manufacture bespoke bats…….. .
The second aspect is the material used and is cleft A better than cleft B. There are visual indicators which can indicate whether a cleft A will play better than cleft B, but as willow is natural you will always get a natural variation irrespective of these indicators. Again, this is where the skill of the bat maker comes into play to make sure that they optimise the performance of each cleft, making an average cleft good, a good cleft great and a great cleft phenomenal – this is all done in the pressing.
Streaky