It could be your trying too hard to focus on too many things at once when you are bowling.  I've learned you can only focus on one aspect of your game at a time.  With me being out of the game for so long and coming back after a 10 year break of bowling league I knew my timing was the big problem and that was the first thing I worked on. That took me honestly almost two and a half weeks to correct and become consistent.  Then I started working on my accuracy by playing a tighter line, which took me way out of my comfort zone in playing so close to the gutter.  That took me additional two more weeks to correct and by playing that tight line It also helped me work on controlling my hook without really focusing on that, so basically I killed two birds with one stone.  Then just recently, I went back to playing in my comfort zone which is 10 and out, and standing on 23 or 18 depending on which ball I'm throwing, and on monday I cranked out a 696 on the new USBC blue oil pattern.  I feel so confident now with my game, that on Monday before league started, I told my team mates, Hey I'm rolling 600 plus guarantee. True story, no lie, and I almost rolled 700. I know for a fact, I could have done better because in my first two games, I had the first five, and then I would miss my mark to the inside and outside on both games.  I know my accuracy has gotten better but it still needs a little bit more work.  I also noticed my adjustments are getting better, but I know there were times that I was one or two frames too late.  

Currently, I am bowling on the new USBC red, white and blue oil patterns.  My house has been laying down, the blue oil pattern type II.  That was another one my obstacles, I was facing when my house change the oil pattern from the THS to this new USBC pattern.  This change occurred in mid. league. Too be totally honest I was struggling to break or even get over 600 on this new pattern.  I had the problem with hitting the pocket too quick or too hard, because I was leaving a lot of 10 pins.  Now that I've learned how to fix that problem and how to bowl on near sport oil conditions I am most definitely feeling better about my game and I should be ready to start bowling tournaments by the end of this year sometime.  

Good Luck with your practice man!
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2010 is the first time joining a league since 1999.  Over a 10 year lay off and haven't lost much of my game.   This year currently HG-279, HS-733.