Although a statement like this is too general to mean much of anything, I doubt that MySQL with innodb (which should be used for most cases) ever bested Postgres in overall performance.
Indeed, (My)ISAM isn't really comparable to Postgres with regard to features anyway (transactions, for one), even if it is faster that's not a fair comparison. Only InnoDB is...
DBMSs are complex things. Any DBA proficient in both systems can show you a query (and table layout) in PostgreSQL that outperforms InnoDB and vice versa.
Although a statement like this is too general to mean much of anything, I doubt that MySQL with innodb (which should be used for most cases) ever bested Postgres in overall performance.