Fitzpatrick did a great job of LEADING the Jets this year.
The operative word is "LEADING." Geno is obviously more athletic, faster and has the bigger arm. Fitzpatrick brought leadership and the team pulled together behind him. Don't diss the Jets...that team turned around dramatically and won 10 games.
To me, leadership is the single biggest asset required in a quarterback. If Geno has taken advantage of his apprenticeship this year, he will have learned a lot about leadership and that knowledge and skill will benefit him greatly.
I'm not sure that leaving the Jets right now would be a good thing for Geno. If he learns and grows, the backup job can help him a lot. If he is patient, and if the Jets are noticing growth in Geno, he could be ideally positioned to take over at QB for Fitzpatrick, who is older veteran who won't be around forever and is not the long term solution.
There is an awful lot of learning involved in becoming a solid NFL quarterback. It will be interesting to see how the Jets handle this situation in the off-season.