Best teenage players I've ever witnessed:
1. L.Ronaldo - During his teenage years, he scored 44 goals on 47 games in Brazil, and 54 goals in 57 games in PSV. Of course then he went to Barca and score 47 goals in 49 games when he just turned 20, with many amazing solo performances. He was simply unplayable and few notches above everyone else during that period, and his pace, dribbling, skills, and finishing is second to none during that period, but it was probably his career peak too. Best teenage footballer ever, period.
2. Rooney - Looks absolutely a beast during his teenage years, he was already a regular for Everton at age 16-17. Scored 17 goals in 43 games for us when he is still 19, despite the fact that he likes to drop back and goes all over the pitch, and his game is much more than just scoring goals. Everyone can easily tell he is going to dominate football world back then, his all round game is probably the best I've ever seen from teenager. Well he didn't quite manage to dominate the world afterwards though, in fact far from it, but he still have a very good and successful career with us.
3. Mbappe - Scored 26 goals in 48 games at age 18, impress in CL with 6 goals in 9 games. Become world most expensive teenager at 180m. He then went on scored 21 goals in 44 games at age 19 for PSG, and impress the world and won the WC at age 19, with 4 goals too. He is now 21, and over past 3 season he scored 90 goals in 121 games for PSG. If he keeps on he could even challenge Ronaldo/Messi record in future.
4. Owen - 23 goals in 44 games at age 18, impress the world in WC with 4 goals and amazing performances. 23 goals in 40 goals at age 19, and then won Ballon D'or when he was 21. He was teenage sensational back then. From age 18 to 23, he average scored around 23-28 goals per season. Probably the most consistent top scorer at that age group too.
5. Giggs - First broke into scene when he was 17, already the best dribbling winger in the league, scoring 7 goals in his first season when he was turing 18 as a wing wizard. At age 19, scored 11 goals in 46 games, and at age 20, he scored 17 goals in 58 games, his career best. And he definitely has far more assists than goals of course (well he is premier league all time best with 162 assists). He was a winger in midfield, full of pace, skills and trickery, and like to cross and assist too. He was probably the best and most skillful winger/dribbler in the world during that period. Let's just say, if we can use the word "wonderkid" on one player only, for me at least, that would be Giggs.
6. Messi - Scored 8 goals at age 18 as a talented but bit part player at Barca, and then scored 17 goals in 36 games at age 19, including that wonder goal vs Getafe. He would definitely go higher in the list if he had played more games during his teenage years (overall he scored 25 goals in 60 games as teenager), but to be fair, back then as an unknown teenager, he has Ronaldinho, Henry and Eto'o ahead of him. He is still one of the most talented teenager ever. Won his first Ballon D'or at age 22, and won 4 Ballon D'or by the time when he reached 25, went on become GOAT.
7. Ronaldo - He was truly electrifying back then when he joined us at age 18, as a winger in 442 midfield. Full of pace, trickery and skills, no one could stop him in the league, and he was probably one of the most talented teenager I've ever seen. Impress in the Euro at age 19, helping Portugal to reach the Final with 2 goals and 2 assists. I wouldn't rate him as high as others above the list as a teenager though, as he lacks abit of end products and was too much of a show pony back then too. It was when he was 21-22, he become truly amazing word class players for us, scoring a lot of goals, making alot of assists, entertaining everyone with his truly amazing performances. Of course, he then went on to win his first Ballon D'or at age 22-23, and later broke every record out there and become GOAT.
8. Sancho - As wing forward, he has 13 goals and 15 assists at age 18-19 at Dortmund. Then this season at age 19-20, he has 20 goals and 18 assists, second only to Messi. He also has amazing skills, he is very good at dribbling and playing a support role too, apart from goalscoring. I mean, for past 2 years as a teenager, performance-wise and stat-wise, he has been excellent. I can't think of any other teenager better than him in terms of goals+assists. At the same time, I can't name more than a few teenagers who is more talented than him.
9. Haaland - Just turned 20 last month. At age 19, he is probably the most impressive teenage goalscorer I've ever seen for a long time. First when I head of him, he once scored 9 goals in a U-20 game for Norway when he was still 18, no big deal, but still make the headline with such record. At age 19, he scored 28 goals in 22 games in just half season in Austrian league, well its very poor league though, but he scored 8 goals in 6 games in CL, now that is very impressive. He then moved to Dortmund for 2nd half of season, scoring 16 goals in 18 games for them, that is again, amazing. So at age 19, he scored 44 goals in 40 games, including 10 goals in 8 CL games. No matter how you look at it, its amazing stats for a teenager. But he is also probably the least talented teenager among this list.
10. Greenwood - He is only 18, but he has already scored 17 goals in 47 games in his first full season. What impress me more is that, he scored 15 goals in league and Europa in 1773 minutes, thats equivalent to around 15 goals in 20 full games. At age 18, he is probably among top 3 best 18 years old in this list? We don't know yet how will he perform next season at age 19, all the above players are a beast when they are turning 19. Maybe his chances will be limited by signing of Sancho? or maybe he will develop in a faster pace then we could imagine?