It's actually quite difficult to compare the performance of Chelsea players because they have a lot of competitors there so when Arsenal are interested in Noni Madueke it means they are looking at it from another side. Apart from that, Madueke is a young player 23 years old well maybe Arsenal wants to implement long term investment, who knows in the next 1-2 seasons his market value will reach 100 million.
A long term investment that will end with the same result, is like Arteta doesn't have a better plans for the Gunners, no bright future. Madueke isn't good for Arsenal to go for him and the way Chelsea allowed him go says it all. When he first joined the Blues without getting that game time, he wanted to leave while complaining and as soon as they start giving him that opportunity it got into his head, a regular starter that felt he can't be replaced and the impact is nothing to write home about. The painful part was that Arteta didn't hesitate on this Madueke's deal, not even up to a week or two and the next thing he's wear jersey number 20 but look at how long is taking him to secure a deal with Sporting CP for Viktor Gyökeres, what a shame.