Right there is your problem, it not a matter of talent its a matter of your workouts being designed to develop speed, turnover, gait, and quality. I knew people both camps with lots of talent as well as little talent but the right works outs helped them achieve their best and neither required that much mileage unless you are focusing on the Arthur Llyarid (sp?) school of running. But again he also includes race specific workouts unlike your routine. Your workouts have been designed to achieve one thing, strength, and proof you can go long miles without getting injured. Both are very impressive, but not designed to improve your 5K time. So the first is to introduce workouts to improve turnover, power, explosiveness and I don't mean trying to appear on ESPN/Reebok/Tough Mudders I mean from only a running perspectiveFirst eliminate the doubles your body is not recovering enough to push through strong workouts. Fartleks are good and should remain as a good way to condition the heart but will not be your key workout.Your key workout is a variation , speed workout. Do this workout Thursdays.2 mile warm up.. stretch... 6x1000M with 200M recovery and over a month build up to 10x1000M but only when you hit these times. Feel it out but they need to be even times. Based on your 18:30 p.r. ... 3:42 is what you typical run at so I'd suggest initially shooting for 3:32 per 1000M with a 200m recovery and then hit the next one again. You want to keep the variance between each low so if there are +/=5 seconds then readjust the goal tmie but it has to be faster then 3:42. Finish up with 1 mile cool down and stretch.SaturdayLift doing explosive but controlled exercises this your focus for the day. To run fast you need turnover to have turnover you need strength and balance. So do balance exercises, squats, lunges, step ups, etc. read up and find a routine that works best for you. Afterwards cross train activity like swimming, eliptical are suggested instead of running to keep legs fresher and remove the acid.Sunday just a single run and a good shake out long run at 10-14 miles.Monday a 6 mile tempo run 80% heart rate/max Vo2 then at then of the run do stride outs. These should be 60 to 80m in length about 6 to 8, they are basically sprints where you focus on your form.Tuesday I'd suggest a 2 mile warm up then you follow that with doing repeats up a gradual incline about 300 to 600m in length. This is too build fast turnover strength, depending on length 6-10. After each your down hill is your recovery when you return to the start. After the workout out is finish rest then do stride outs as previously described. Finish with 2 mile cool down and stretch. On this day again lift to focus on strength and balance again with activities like lunges, step ups, squats. You are doing this to build lean strength and improve balance which improves running power and your overall speed.Wednesday should be a shakout run with the idea your real hardwork day is coming up. Do something like 6-8 miles at a good tempo but not strenuous so you have strength for the next day workout.Thursday the workout to improve turnover... over time you will also alter this like doing 6 repeats but at full 1600m distance. The key is this workout should be on a track. Other weeks you will only do 400m repeats but 10-12 again all depends on your needs and how you respond.Friday easy run.Goal total mileage can be between 50-80 a week but with more quality, like hill repeats, track speed workouts, lifting, etc.Good luck. I used that 10x1000m workout to hit modest P.Rs but ones I'm proud of 15:19 for 5K on track, 31:50 for 10K.