Chelsea football club contract extension doesn't make sense to me and we don't know why they do this but they have their reasons. Jackson is said to have done well in the eyes of the club owner therefore the contract extension was a reward for his performance last season. While we didn't see anything that Jackson did, the club saw and thought it'll be good they extend his contract. From this new wages, Jackson should be performing better or he's going to be benched when Chelsea get a new striker. Jackson doesn't have any plans of leaving the club as no club will want him with the way, he's constantly missing chances created.
I also don't think Chelsea should have extended Jackson contract. He didn't do well last season so it is hard to understand why they did it. Maybe club owner saw something special in him but it is not clear what that is.
Jackson has not played well and has missed many chances. Giving him new contract and more money means he needs to do better. If he does not he might sit on bench when Chelsea gets new player. Jackson is not playing well enough to join another team so he will probably stay at Chelsea. This decision is risk and we will have to wait to see if it works out. For now it is confusing choice that makes us wonder about Chelsea plans.