League of Legends (LoL) Question: Why Pro Player Doesn't pick The W Skill on Singed ?

The above comments explained it real well. Basically, you need the extra Fling damage to come out above on early trades. Literally the only time the slow would be useful is if you're being ganked or someone is ganking for you and even then it isn't that good.

Not to mention the huge amount of mana it costs. Using your W, then E, with poison on would annihilate your mana pool early.

Because top lane is trade-intensive and every bit of damage on Fling counts.

Mega Adhesive doesn't help you in trades at all, and you have your Ult or Ghost to chase people at 6 anyway.

I never pick W till I must due to Singed need more damage for Q and E. For your question
Try this my gameplay without pick W.
https://www.youtube.com/watch?v=tHtmJumPGEw

I actually beg to differ ... depends on the situation i just got off from a game where i was support singed but the ADC afked right from the start by lvl 3 i pick up the W spell because they were playing aggressive to i would fling one to the tower with the stick and would secure the tower kill assist....
ending the game with 28-9-20 for my score
http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/1977064672/220292980

Read the mobafire guide by Best Singed NA; I'm sure they'll explain it.

Singed is not an early-game champion, so his damage is pretty low until he gets some items. Also, Mega Adhesive costs 70 mana at rank 1, which is a lot in the early-game, making it inefficient until you have both damage and mana to utilize it.

the slow sux at low levels and since you dont max it its kinda useless early game, so you just get it when you have to. once its maxed its a strong slow but maxing fling and poison is way more important.