Raising Won when saw flop stat?

[Evoken]

Just glancing over the stats thread, I can't seem to figure out how some of you guys are getting 42+ won when saw flop at 10nl. Until my last 20k hands, over all levels I was able to get it up to around 37 on average. A pal of mine who plays 10/20 and helped me get started in poker recommended I tighten up alot from about 20/16 to 18/14 preflop, and for the past 20k hands it hasn't been working too great. I'm pretty sure it can't be correlated like this, I've kept my post-flop game 100% the same and just tightened up preflop a bit. My won when saw flop suddenly dropped to only 30.5 and my EV graph green line plummetted below the blue and red lines. I didn't change anything about my post-flop game and this has been really frustrating. I'm only doing basic c-bets and never doing c-bets oop unless it's a HU pot or if I have a reasonable draw when it's multi-way. I'm double-barreling very rarely, only with lots of outs like with combo draw+overcards. Very rarely I'll double barrel on a dry board if a scare-card comes if it's a good villain to do it against, but I've only done that about 10 times my last 20k hands.

Is won when saw flop just a stat that can fluctuate alot when you're running good/bad or is there some leak I have? Any tips/advice would be appreciated, thanks. I've also been running pretty awful in showdowns lately, 20% went to showdown 47.5% won at(20k hands), is that dropping my won when saw flop a ton?