Aloha got it right, but let me comment...
Good wins are wins against players with "higher rankings" than you overall. Note that when we calculate our Tennis Recruiting rankings, we first create a master rank list that includes all players of the same gender - that master rank list includes players of all ages, graduation years, etc. Note also that only results are used in the rankings - age, etc. does not factor into the rankings.
Once we have the master ranking list, we then filter out the various graduation years to create the 7 lists for 6th-12th grade.
So... wins against players significantly above you in the master rank list are "good wins". Losses far below you are "bad losses". Almost every player has a handful of wins above and a handful of losses below - but most wins are over players ranked below them.
Addressing the original question directly...
Originally Posted by Tennischick
If I beat a blue chip 2 years older than me is that as good as beating a blue chip 2 years younger than me?
The rule of thumb is that "older kids are better than younger kids". The No. 1 senior is usually higher ranked than the No. 1 8th-grader in our master rank list, and a Blue Chip senior is usually ranked higher than a Blue Chip 8th-grader as well. However, there is nothing to say that this is always the case... a freshman phenom that wins, say, Kalamazoo, might be ranked higher than most Blue Chip seniors. In this case, beating that freshman would be a stronger win.
So, to be precise, age/graduation year does not factor in directly - except insomuch as older kids are typically ranked higher than younger kids in our master rank list. But yes, beating a Blue Chip 2 years older is almost always worth more than beating one two years younger.
I hope this helps.