Special Place of Baal Teshuva

There is a statement of the Rabbis that needs some explanation. It is said that the place reserved for the Baal Teshuva, places him on a level that is higher than one who is a complete Tzaddik.

This statement seems a bit unfair to the righteous. Can they be penalized for being good all of their lives? This question is answered by “The Duties of the Heart.”
Rabbeinu Bachye wrote of three categories of Baal Teshuva. The first category refers to those who have been lax in the observance of positive Mitzvot. They have not been wearing Tzitzit, or putting on Tefillin. They not bother to sit in Succah, or bless the Lulav.
When these individuals resolve to actively observe these Mitzvot, they are on the same level as the righteous who have never been deficient.

The second category is the one superior to the Tzaddik. This refers to the group that had been violating various negative commandments. Perhaps they were guilty of eating forbidden foods or speaking Lashon Hara, or other commandments where lashes would be given.
When they demonstrate humility and remorse and no longer violate these Mitzvot, they are on a higher level than the born Tzaddik.

The third group can never reach the level of the Tzaddik. They may have been guilty of Chilul Hashem, desecrating the Name of G-d. Even if they do Teshuva and show regret, they are not fully forgiven until they die. Repentance is welcome but the grievousness of the sin does not allow them to reach the level of the true Tzaddik.

This is a very plausible answer in explaining the special place reserved for the Baal Teshuva.