if i ever have a tennis blog (please don't let me do that), this is my first choice of title. now, i know what you're thinking: "hang on, i remember learning tennis scoring, and it's definitely 40-all that's deuce." well yes, but it turns out that actually they both are. need proof? from either score, there are four possibilities of what can happen on the next two points. server wins both 30-30 -> 40-30 -> game 40-40 -> ad in -> game
server wins one, returner wins one 30-30 -> 40-30 -> 40-40 40-40 -> ad in -> 40-40
returner wins one, server wins one 30-30 -> 30-40 -> 40-40 40-40 -> ad out -> 40-40
returner wins both 30-30 -> 30-40 -> break 40-40 -> ad out -> break
fine, whatever, it's a quirk of terminology. what's the big deal? well, the big deal is that match commentators treat these two scores very differently, when they are theoretically identical. 30-all is frequently called "an opening", "an opportunity", "a half-chance", among other turns of phrase that are full of optimism for the returner's odds of breaking serve. (less commonly they frame it as trouble for the server, but the direction of bias is still the same.) but 40-all is just deuce, and treated as relatively equal. if anything, the server's general expectation to hold biases the commentary in their favor at 40-all.
i'm really baffled what has created this altered perception of 30-all vs. 40-all deuces. the only objective difference is that at 40-all deuce, one of the two players has necessarily missed converting a game point. someone has already had a real opportunity, so perhaps speculating on half-chances and maybes is thrown away then? but the reality of what could be and what must be done remains unchanged. i wonder how many players even realize the equality of the two scores, and in terms of psychology and strategy, would treating them as the same or different produce better results?