Santos was an above-average team before he arrived. Same as napoli with Maradona. They took average teams to new heights.
In contrast, Messi arrived to a top team, and CR7 the same, with Real Madrid.
Besides, South America before the 80's was a soccer powerhouse. Premiership didn't even exist, and the league was a backwater for fishermen journeymen and player-coaches. It took a lot of time for the color TV (and TV broadcasting in general) to get going and tilt the balance for Europe.
If you played exhibition games you played against south american teams, and usually in south america, to make any money and to see any quality.
Penarol, Estudiantes La Plata, and a few others, massaccred regularly all of the big names of today.
It was only when super south american players started migrating to europe because TV money arrived, that things changed.