This won't sound like a idea dripping with performance inspiration, but consider this.
Your success will not be determined by your very best performances and it will not be de-railed by your worst. It will be determined by how good your 'average' is.
Your average of course is determined by the sum of your performance scores/the number of performances. Mark a performance out of 10.
Here are five performances: 2/10, 8/10, 9/10, 1/10,4/10. Wow, an 8 and a 9 in there, good job! Let's sweep the others under the carpet eh?!! The average = 4.8.
How about these five?: 6/10, 7/10, 5/10, 8/10, 7/10. That's an average performance of 6.6. Never quite hitting the dizzy heights, but pretty much just 'normal'.
The reality is that most of our performances will sit somewhere between 4/10 and 7/10, in the average to normal band. It's tough to be right up there at your very best consistently (8-10) and its unlikely that you be at your very worst (1-3) that often, so most of your performances will sit somewhere in your 'average' zone. This is your 'normal'.
The key then, is to raise the quality of your normal or even take it a step further as Martina Navratilova once commented:
'The mark of a great sportsman is not how good they are at their best, but how good they are at their worst.'