Ok, so according to transfermarkt:
Bolasie has played 119 times in the premier league.
he has 11 goals and 23 assists
that’s a goal every 10.8 appearances
and an assist every 5.2 appearances
Fraser has played 120 times in the premier league.
he has 16 goals and 29 assists
that’s a goal every 7.5 appearance
and an assist every 4.1 appearances
so according to these stats fraser’s goal/assist per appearance record is significantly better than bolasie’s.
obviously you could go deeper with stats. Things like goals/assists per min are better than per appearance. Also I think chances created is better than assists. It’s unfair that bolasie was supplying Niasse and DCL (before he turned good) and Fraser was supplying Calum Wilson who is actually a really good finisher.
having said all that, I’ve seen bolasie play for Everton and no longer want him at the club (though he was decent before his injury in 2016).
fraser may be slightly better but I don’t want Everton to give him the 5 year 120k a week deal he will get from some mugs as a free agent this summer.
5 more goals and 6 more assists in 120 games is not "significantly" better.