Everything is fair and square in bowling as long as "I WIN"
Otherwise...
1) opponent got too many breaks
2) I got screwed
3) Lefties have an advantage
4) Lefties are shut-out
5) Bowlers get too much HDCP
6) Scratch bowlers shouldn't be in HDCP brackets
7) Not enough oil
Too much oil
9) Didn't bring right equipment
10) Sandbaggers
Feel free to add your own