You're bowling better on sport shots vs a house shot?

For the past 2 months i have bowled better in tournaments and practicing on sport shots (35', 39', 41', 47', 48'). I'm struggling to shoot 600 on our house shot and have dropped my average 10+ pins both nights i bowl but I've probably averaged 210 the past 2 months for about 35-40 games on tougher shots.

It's just frustrating for league

i have the same issue as you. people who through the ball well tend to do worse comparatively in house patterns. to bowl well on sport patterns you generally have to throw it pretty good (clean, consistently, maybe decrease axis rotation) and control the backend. transition is most predictable due to the cliffs not being so extreme.

house patterns promote the exact OPPOSITE. it with it being so wet/ dry it promotes more axis rotation to exploit the backend, allows inconsistencies in release, promotes grabbing and hitting up on the ball due to the extreme wall oil line. sport  bowlers' releases are too clean that the ball cant read the flood on pulls and over reads friction on misses out. that is why sport bowlers tend to have less gap or no gap in their house average and sport average.

I have low tilt and lower axis rotation.

It's also been frustrating because it seems the house shot has no consistency week to week and even lane to lane. I feel like I'm constantly fishing on the house shot and the tougher patterns are more predictable.

We're almost identical.

I feel like the people that benefit from a ths, style wise, are those really cranking left to right or slow rolling the 8 board. I think those of us more in the middle run into oddities.

 Some people bowl, some throw the ball.

 On a house shot, those who throw the ball tend to get rewarded for "bad" shots.

 Those who bowl don't throw it "bad enough" to benefit from a ths.

 Chunkers don't throw it "good enough" to score on tough shots.

 That's why bowlers prefer tougher shots, and chunkers prefer ths.

I bowled on high friction surface with a 37-38' pattern around the time I bowled that sport league at another house. I too have very low tilt and struggled in the short and low volume pattern.

I found out later that the league bowlers in my handicap league had complained about the 40-41 pattern to management. So amf had to make these older folks happy. It was mostly seniors in the league who had complained.

The funniest thing.. There was this JOE bowler who never hit the same spot down lane and carried a lot. Pretty to Ugly shots, he carried a lot and talked a lot. I never got to bowl him all year and One day after running his mouth, I invited him to bowl with me in the up coming sport league. AND he turned away without saying anything but "Uhmm..." 

but when

It is not a case of house shots rewarding wild shots.  House shots do not reward errant shots.  They do not punish small errors as much, but there is a difference.  House shots reward more powerful releases in terms of carry.  Most people who average better on tournament patterns are accurate lower rev players who do not carry as well on house shots because they are forced to hook around the heavy oil in the middle.  I have several times over the years averaged as high on a variety of tournament patterns as I have on house shots in the same center.  Higher rev players may not make any bigger mistakes than I do, but their high rev rate magnifies small mistakes more than my low rev rate does.  In addition most tournament patterns allow me to play more direct with my forward roll, which enhances my carry.   On house shots my carry varies tremendously.  Very common for me to shoot a couple of sets under 640 with poor carry, then fire a 740 on when the shot really doesn't seem any different.   

Bottom line, the biggest factor that determines how we match up to a pattern is the length of the oil on tournament shots.  I can average almost as high on a Cheetah or Badger as I can on a house shot, but I am not going to average close to as much on most 40 foot patterns.  On house shots it is less about the length of the oil, because we can control how quickly our ball comes out of the oil by controlling how quickly we get the ball outside the heavy oil line.