It’s where the cork meets the metal. Or where the Rulon meets the cork. Or maybe it’s just a small metal triangle bouncing along a gear. Whatever drag system lies hidden behind the frame of your favorite fly fishing reel, you want to feel confident that it does the job it is intended to do. And as Zach Matthews points out in “Brake Jobs,” a little overkill never hurt anyone. This week’s addition to MidCurrent is a thorough look at the drag systems available on popular fly reels.