“Nothing in the world can take the place of Persistance. Talent will not. There is nothing more common then unsuccessful men with talent. Genius will not. Unrewarded genius is almost a proverb. Education will not. The world if full of educated derelicts. Persistence and Determination alone are Omnipotent" (Joe Strummer; former lead singer of The Clash). On a related note, I am a firm believer in the "10,000 hour rule" (see, for example, Malcolm Gladwell's Outliers). That is, it usually takes 10,000 hours of focused work to achieve success in any given field.
Unfortunately, so many people - particularly parents - hang their hat on talent alone. Often times, I am told by parents that some other coach (sometimes "reputable" a lot of times less than so) regarded their child as "talented". They tend to use this unscientific evaluation as almost a form of justifying skipping out on hard work. Don't fall for this snake-oil! Tennis is not easy; IT'S NOT SUPPOSED TO BE. THAT'S WHAT MAKES IT FUN AND ADDICTIVE.
From my point of view - and realize that I may be wrong (although I am not the only one) - nothing is more OVERRATED or DECEPTIVE as talent. I say that talent is overrated because (a) talent will not get you to the ball; (b) talent will have no bearing on how hard your opponent will work or what he's capable of doing with the work; or (c) talent is insufficient to make you dig deep when you're running on fumes deep in the third set.
Talent, may however, make it somewhat easier for a player to pick up strokes or concepts. This leads to the second criticism in that talent is deceptive. A lot of "talented" players tend to get lazy; they may have early success due their ability to learn quicker than other kids and continue with the same training regimen (e.g. 1 hour a day) throughout their developing years (14 and over). The fact is that 1 hour a day on the court may be sufficient when you're 8, 9, 10 or even 11-12, but it's just not enough when you're moving on to the development stages (Cf. learning stages) of the game.
As you get older, tennis becomes serious business; there are a lot of players throughout the world who intend to make a living at this game. As a result, they spend hours and hours on the court or in the gym, learning all parts of the game and tempering their bodies and minds for the tough battles. Talented little Johnny who spends an hour a day (maybe) of unfocused hitting will have NO chance against these animals.
So my advice is to either remove the word "talent" from the vocabulary or know that, in the great scheme of things, it's meaningless. Beware of snake oil salesmen who sell you the quick-fix (e.g. "she just needs to work on angles" or "he just needs to improve his serve") or gimmicks. Know that hard work - be it in tennis, medicine, law, accounting, computer programming, business or digging ditches - IS THE SHORTCUT; and you have to love every minute of it.