Mike, can I ask what the "High level" of football you played at was?
In terms of your 5ks and general development, it's a very tricky line to bridge between encouraging you and being realistic.
The realist in me knows that my slowest 5k ever was 18:18 from similar mileage to you. I also recognised in 6 years this has "Only" gone down to 17.10. If I actually found a proper flat road course, and targetted the distance, I'm sure a sub 17 would be doable.
Therefore, i'd have to be blunt and say that unless you were running those 5ks with a pipe on, and strolling it, the chances of you beating 16.05 within 3-4months are absolutely zero, and the chances of you beating that time if you continue with football will be massively reduced as well. You don't run low 16s for 5k casually, unless you're blessed with very good ability.
Little stat for you, only 202 runners beat 16.06 at a park run in the whole of 2011, and a lot of those results are classified NAD, "Near as damm", ie might not even be full distance.
What you do have though, is youth on your side, and high keeness. Those will get you so far, and then it'll be on your natural ability, which noone can really be sure of.
Edited: 01/08/2012 at 21:15