Lee, traded to Texas on July 9, along with reliever Mark Lowe for first baseman Justin Smoak, Blake Beavan and Josh Lueke, makes his first appearance at Safeco Field since the deal.
Vargas said he tried to learn as much as he could from Lee and it was like going back to school.
"We pitch a little different, but he talked about different ways of pitching different guys, lefty versus righty," Vargas said. "It's something you always chat about on the bench.
"But he's a Cy Young Award winner and anytime you can learn anything from how they do it, it's pretty cool. He worked quickly. He wasn't afraid. He came right after you. He pounded the strike zone. He's not going to walk you, he's going to make you put the ball in play, or make you miss it."
Lee also talked about the importance of not letting the opposition know how you felt on any given day.
"One of the things that stuck out, and something my dad had told me a lot when I was growing up -- and this was in a meeting in Spring Training -- is that regardless of whether you have your A game or your D game, nobody else knows that but you.
"You have to go out there regardless, and you're the only one who knows. So just pound the zone and what happens, happens."
Vargas happens to currently be on a five-game losing streak, dating to Aug. 14.
"I don't think I've lost anything. There were some games I lost. ... The game against Minnesota I didn't really get hit hard. Balls fell through and I lost that game. In New York, there was the first inning. I don't think I've thrown the ball badly, or any worse than I did early on. Different things happen in the game.
"The game I threw against the Angels in my last start was one of my better ones."