I meant when his speed and power drop to below 5, you'll be able to boost them back up again as he was born with golden power and speed. So it will be a relatively short timescale (depending upon your TC level and staff). 100% for the first one and 120% for the second. So he has greater longevity in your squad.
It will probably be a couple of seasons before you need to do that, so initially you can just concentrate on boosting his scoring.