Not Good Enough
A positive mental approach can be the key to improved performance...
BUT sometimes it's fine to be honest...
" It's not good enough" is probably a little direct and harsh for young developing swimmers...and a little vague
" It's Ok..it's fine....it's solid...but you are better than that" is probably a little more appropriate for young swimmers on the cusp of performance focus; particularly when mixed with positives from the race eg good start, clean entry, etc.
Ryan Lochte often comes out with some interesting comments but this interview is quite insightful. Depsite winning several titles and producing world leading times at the USA World Trials he says " It wasn't good enough"
http://swimswam.com/lochte-says-world-trials-performance-wasnt-good-video-interview/
Enjoy!