A theoretical idea: what if it was Galen Marek, not Obi-Wan who 1st trained Luke?
If Galen Marek (Jedi) survived the encounter, would he have been a better Master to Luke before Yoda? You have to take into account that Galen was younger and physically stronger than Obi-Wan and at times seemed stronger in the Force than Obi-Wan - opinions anyone?