Who are you trading out to bring these players in?
One thing to remember with Simpson (150SC), it is likely you have missed his highest score for the year. It was his second highest Supercoach score ever from what i could find. This means that if you pegged him for a 95 average (22 games) before the season and this holds true, he will average 92.4 from here. On the reverse, if you had Hibberd pegged for a 95 average (22 games) and this holds true, he will average 96ppg from here. It may not seem like much but it's about 75 points for the season.
These are some great points and I'll need to consider.
In answer to your question, I would be looking to upgrade Naughton to Simpson with some spare cash (also helped witha potential trade of Brayshaw to Geelong Fogarty). I already have Hibbo and am planning to keep him.
Your point re Simpson is a good one, but the way I'm looking at it is that he is priced to score about 92 so I wouldnt be overpaying. Further, he should be a top 6 Def and I would be wanting to bring him in at some stage anyway. Finally, if he continues to play the role he did on the weekend, then he should be a good chance to average more than 92 from R2 to the end of the season so still represents some sort of value.
Doing the trade now would be an aggressive move and it might be more acceptable to wait another week to see if anything else changes. Team sheets might influence which way I jump.