Fercita

I say one thing is to be inexperienced and another is lacking a common sense and another is being manipulable. Leonard is manipulable because he still thinks he has to do something to please the woman. He is manipulable because he still let Priya tell him what to do and he does it, and he recognizes it "Yes, ok, like always".

He is manipulable because he let Stephanie stay even though he wasn't comfortable and because he wanted the sex.

Priya is manipulative, but Leonard does what she asks to do. You don't have to have the experience of the elder to have common sense, he just does it to please his girlfriends. What real difference does it make if he wears contacts or not? I mean, what could he think he could benefit from bumping over everything? Nothing, he did it because Priya told him to. He learned football because he wanted to mingle with Penny's friends, to have her girlfriend's approval, to stop Raj's train of thought that "Penny thinks Leonard is a little geeky guy who likes to fly kites". He later revised that when he really didn't enjoy the game and thought that his hobbies were not worth something he did not to share his girlfriend's hobbies, but to mingle in her group.

Being manipulable doesn't just mean obeying orders, but being led by outside expectations in society. He wants to mingle, thus, he is manipulable.

He was manipulable when he thought "I...it's just, I need a woman" no one told him to do get a woman, yes it was just a suggestion, but he still did it.

ETA: You could still be manipulated by your own perception of things. And Leonard does that. He thinks this, he thinks that, even if he doesn't agree he thinks he should do it. That he needs to do it.