We have been debating whether it is possible for the two players to raise their level of play without changing the AM's.
I would like to present a hypothetical scenario in which two players playing on two occasions on the same surface exhibit different level of play yet their calculated AMís stay the same.
It is open to debate if such a scenario is realistic.
On the first day they played an average match; winners, forced and unforced errors were counted, and the AM's were calculated.
On the second day they played an excellent match, however the number of winners, forced and unforced errors was the same as on the first day (for the sake of simplicity I assume that the number of points in both matches was the same). How is it possible?
The first player was hitting great shots, however the second player was also defending better than previously (had the second player been playing as well as on the first day, the first player would have had more winners than on the first day, had the first player been playing as well as in the first match he would have had less winners than in the first match). As a result the first player had the same number of winners on both occasions, and the same applies to the second player.
Generally the same logic applies to forced errors. Both players committed the same number of forced errors as during the first match, however the shots that forced these errors were of the higher quality than the shots that forced errors in the first match.
Generally the same logic applies to unforced errors. Both players committed the same number of unforced errors as during the first match, however the points which ended in unforced errors were of the higher quality than points which ended in unforced errors in the first match. We have already mentioned that points that end in an unforced error may be of different quality (e.g. long neutral rallies versus double faults or return errors or short neutral rallies).