I attribute this tough streak to three things: 1) The level of play has gotten tougher. I don't know what to attribute this to, but play has gotten really, really tight. My "voluntarily put money in pot %" stat was at a respectable 23-25%. Experts say that it should be at about that level; higher than that, you're playing too many hands; less than that, you're playing too tight and leaving money on the table.
At PartyPoker, at PokerStars, and (after Party shut down in October) at Full Tilt, at a 9 or 10 person table, I was usually the second or third tightest; seven people played looser, and I could usually end up with some of their money. In the last month at Full Tilt, my stat has been the same, but I've generally been one of the three loosest people at the table. The opposition has tightened up. 2) I failed to adjust to the tighter play, and plays that would have won money in the past -- strong bluffs -- either won a minimum, or lost big. Holding AQ on a flop of 479, I could ram and jam, and would win a big pot against someone wishing with another couple overcards when they folded on the river. Now, I either don't get past the flop, or lose to someone who stayed in with a flopped set.
3) Related to #2, I failed to respect strong betting. Before, there was always one or more players who seemed to raise preflop with any single face card. Someone was always drawing to the flush, and it made sense to make them pay. With the stronger players, you can't profit from these mistakes as often.
I took a full evening this weekend and instead of playing, I used PokerTracker to analyze my stats over the last three weeks. Mistakes I saw in my own game, which I made repeatedly or which cost me a good sized chunk of change:
1) Holding two overcards (e.g., KJ) and a flop comes paired (e.g., 3-5-5), I bet to try and win, and it's raised. Instead of respecting the raise and folding, I doubt the other player's skill, and re-raise. Lost a lot of money doing that.
2) When I'm holding top-pair-top-kicker, and I'm check raised, I should fold more often. There were at least a dozen times I ran into someone who'd flopped a set, and I just bolted blindly along through the river.
3) When I hit trips, and the board has two suited cards (e.g., I have J♥ J♦, and the board is J♣ 3♣ 7♠), don't slowplay. Someone who is staying in is trying to hit their flush card, and will do so to beat you 40% of the time. Don't give them a free chance to do it.
Yes. PokerTracker is worth picking up.