Did uncounted overseas ballots give the lead to Franken in Minnesota?

A shameful total of 98,000 of 441,00 ballots requested by Americans overseas in 2008, mainly military personnel, were never returned. 

Assume Minnesota's share of these unreturned ballots was proportional  to its share of the US population, or just over 1.7%.  That would equate to about 1,700 ballots.

Franken's lead over Coleman is just over 300 votes at last count. Could these mainly military ballots have made the difference? 

It seems quite possible (Coleman would have needed to win 60% of all these ballots to overcome Franken's lead).

Why exactly were so many ballots(over 20% of the total requested)from military personnel not received or counted?