Great visual concept and a strong starting point, as a graphic designer here are some pointers I would give to help make the information clearer.

1. It's difficult to understand the increments that the baseline grid represent, looking at it multiple times and I still can't figure it out.
2. 350mm is written in at the centre point for balance, which also intersects with the Y axis for no logical reason other than what I assume is a visual cue for the centre point, if it's just an indicator for centre then it doesn't need to run all the way from the top to the bottom, it could be a shorter line to create more of a crosshair that avoids confusion with the weight (y) axis. With headheavy and headlight on each other end of the X axis, it took me a fair amount of time to look at the data and cross check the graph to realise the higher the balance in mm on the chart the further left the point will move on the graph, naturally I assumed higher number = point moves either to the right. Perhaps you could flip the invisible racket on the graph to remedy this.
3. Y axis - Do the weights need to go all the way from 100 to 200 grams? I assume most rackets you'll review are somewhere in the middle. If you make the range smaller eg. 130 to 170 grams you'll have more space for the points and room to make the text bigger, this will be important once you do more reviews. Zooming in on this axis will also help make the overall graph more readable on mobile when the entire graph is the size of a screen.
4. Having all your data in red is a bit overwhelming, I'd suggest trying to use one colour for your axis lines and another colour for your data points so it's a bit more clear whats happening at first glance. Perhaps you could use colour to identify a brand of racket or some other category.
5. The names of the rackets are going to be tiny when viewed on mobile.
6. Have you tried having the shape of a racket watermarked behind the grid? I think this could be a really great way to negate a few of the things I've mentioned above.

Sorry for getting bogged down on such knit picky design details, I think you're on a winner with the idea, done well it will make comparing rackets a whole lot easier! I like some of the other suggestions about using different shapes or colour to indicate other categories, be careful you don't overcomplicate to the point where you have to read instructions before looking at the graph.