Ash is far from a bad Trainer.
Consider that about half of the Pokemon Trainers who start off don't complete their first year on the road. They don't even make it to the 8th Gym. They never reach Pokemon League. They go home. Then there are Trainers who take over a year to get their eight badges. They might be out there years before they even see the Pokemon League. Even after all of that they might make it to the Pokemon League only to get crushed by a more experienced Trainer in the first round. Then they're back at square one, taking 1+ years to collect a badge, only so they could do slightly better next year. Ash is a Trainer who's not only qualified for the Pokemon League in the first year but one who has consistently placed in the Top Percentile of Pokemon Trainers who compete.
That's not even counting his wins in the Battle Frontier and Orange League.