Most was already said above.. he had a lot of gear issues, wrong enchants, under haste breakpoints by a little, was under hit capped. But gameplay issues aswell, wrong use of CDs, horrendous uptime on the dots and nature's grace... etc.
Suggest he should read a bit more info on the class, that's the most you can do honestly.
Other then that, already said aswell, balance is one of the worst class in terms of perfecting dps to each fight, as we're highly dependant on circumstances. Lust\CDs upon entering lunar... just reaching solar for AoE bits for best shroom\hurricane use, renew dots on new eclipse+forced movement, so on so forth. It's one of the hardest classes to play in that regards, as others just follow their rotation and have no concern on the fight mechanics. Makes it more fun for me