Nothing brings me out of a writing slump like someone posting something about win rates.
The post in question today was by Chris Wheatley from Football London:
The main thrust of the article was about how Cedric is the better choice at right back because when he plays there Arsenal win more often.
This is certainly a true fact but looking at things just this way is incredibly misleading. This isn't to dismiss the idea that Cedric is a better choice for Arsenal, and I have already compared them previously so I won't wade into that argument again.
What makes this measure so misleading is that it doesn't account for the strength of opponents at all, nor that draws also get you points and can be good results as well (or even a loss that still has the team advance like the last match against Olympiacos).
To illustrate the differences between the level of teams that each has played against, I used the closing betting odds and coverted those into the implied odds of Arsenal winning. This makes things look quite a bit closer.
You can see that Arsenal do win more matches when Cedric Starts but they are also expected to win more often in the games that he has started. The performance for Bellerin also matches much closer to the expected winning (but slightly below expected).
To put things in a bit of perspective, in the matches Cedric has played Arsenal are epected to take 2.1 points per match, it is 1.9 for matches where Ainsley Maitland-Niles played Arsenal, 1.8 for the matches played by Callum Chambers and 1.6 for the matches that Bellerin played in.
There are certainly reasons to point to if you want to say Cedric is the better option but using win rate is a poor choice.