I like where you're going with this, but it's a little messy right now.
Always a good idea to start off with words like "Before", "When", "After, or "As". This forces you to "answer the question".
You have some extraneous info in the logline, which is "prime real estate" for words, as you want to limit it to 30 words or less.
The letter is not posthumous; this implies it was written AFTER the father's death; finding the letter posthumously is the correct sentence.
I like either title, btw.
"When a basketball star learns of his own childhood abduction and the time lost with his father, he struggles with emotions and fears that puts the national championship in jeopardy."
Geno Scala (sharkeatingman), judge.