You can look at it both ways really. At Arsenal we have multiple attacking threats so you can't really focus on setting up your side to nullify Fraser if we have devastating attackers like Aubameyang and Lacazette. At Bournemouth he is their main creative outlet so managers will be looking to target someone like that.At Bournemouth. Defenders playing against him at Bournemouth are giving him more time on the ball than he'd get playing for us. No-one raises their game against Bournemouth.
Its a similar situation to Zaha at Palace, except Zaha is literally a one man team at times.