Also it was said on the show that the League of Shadows training is above Oliver's. Olli wasn't sure what to expect and what he was fighting when suddenly a new archer showed up.Slade forced Ollie to engage in beast mode. He was rusty when fighting Malcolm. That's my assumption. Plus, Malcolm is a fucking boss.
Plus, we don't know if Ollie beat Slade in a fair one on one fight. He did shoot his eye out.
Also, this is really exciting. We basically have 4 different villains and 3 different storylines for the next half of the season- we've got Malcom and the Dark Archer storyline, Ra's al Ghul and League of Shadow storyline and Broother Blood and Deathstroke storyline. My bet is that Deathstroke is the lead villain this season (both on the island and in Starling City). Ra's will be used to get Laurel into Canary mode and Malcom will bide his time to come back like a true villain in the later seasons.