Lleyton Hewitt tends to be way underrated by some people today, who seem to have forgotten how good he once was.
When Lleyton Hewitt was a teenager, I thought Hewitt was going to be the next big superstar in tennis, i.e. that he was going to be Sampras' replacement. But he was far more exciting to watch than Sampras IMO, and what really impressed me was his mental attitude. I was a big fan of Hewitt from the moment I saw him play. He reminded me of a football (soccer) player who uses a lot of passion in matches.
Hewitt was mentally ready for the tennis elite almost from the start of his professional career, whereas other guys of his generation, including Federer, took years in putting all the pieces together mentally.
In 2000, he started the year with a bang and people were talking him up as a huge star of the future and some were even backing him to win the Australian Open there and then until Magnus Norman beat him. Hewitt rose up the rankings fast and was becoming better all the time, and made his big grand slam breakthrough at the US Open that year in getting to the semi finals and winning the doubles title with Max Mirnyi.
In 2001 and 2002, we saw Hewitt's best years in terms of results as he finished both years as world number 1, won the 2001 US Open, 2002 Wimbledon and the Masters Cup in both years, providing us with some thrilling matches. Hewitt also won 2002 Indian Wells. There was also his perfect performance at Florianopolis on clay in 2001 Davis Cup when he played 3 matches, a singles match against Meligeni, a doubles match with Rafter against Kuerten/Oncins, and a singles match against a prime Kuerten, and Hewitt won all 3 matches without dropping a single set.
I thought that Hewitt was only going to improve further in 2003, especially after he won his second masters series shield at Indian Wells, but instead he had a wobble and become much more inconsistent. Him blowing a 2 set lead at the French Open against Robredo after playing perfect clay-court tennis up to that point, was massively out of character. Jason Stoltenberg quit as his coach after that, Hewitt looked sluggish at Queens where he had been 3-time defending champion and then had that awful first round loss at Wimbledon to Ivo Karlovic, the lowest point of Hewitt's career.
But Hewitt somewhat rescued something out of 2003 with those phenomenal Davis Cup 5-set wins against Federer and Ferrero, the former particularly, and Hewitt looked like he was getting that consistency back. In 2004, I honestly think Hewitt was starting to play his best tennis ever, but the only problem was that Roger Federer was about to hit his prime, and Federer handed Hewitt some very tough losses that year. Hewitt was in the matches at the Australian Open and Wimbledon, but he was thrashed out of sight in Hamburg, the US Open and the Masters Cup. In 2005, Hewitt had a phenomenal run to the final of the Australian Open, but a similar pattern to 2004 continued as the year enfolded with Federer beating Hewitt regularly in big tournaments, only Hewitt was now starting to be dogged with injuries for the first time, which forced him to miss the clay-court season and the last months of the year.
After 2005, Hewitt's speed, that he relied on so much, was reducing somewhat due to injuries, and with a player of Hewitt's style, a loss of speed is going to affect your game a lot, especially in regards to playing at elite level. Since then, Hewitt has still given us some great and exciting matches, but he hasn't played at elite level on a consistent basis since 2005.
Those who say Hewitt has overachieved are very wrong, because he has massively underachieved. Without Federer around, Hewitt is a probable 7-time slam winner across 3 slam tournaments and with another Masters Cup to his collection, which would have been a vast improvement on what he has achieved in actual reality. He was recently voted the third best player of the noughties behind Federer and Nadal, even ahead of Agassi. A great achievement.