I think I heard that statistically they have a 2% chance of making playoffs
You either heard wrong or are listening to the wrong people. The Red Sox are still the best bet to make the playoffs out of that division are probably still the safest play in the AL, though the Rangers are certainly looking better and better.
Following this 0-6 start, Fangraphs has revised its projection of the Sox' total wins this year from 98 wins to 94.4 wins. Baseball Prospectus has revised downward from 96 to 94 wins, with still a 54% chance of winning the division and an 83.5% chance of making the playoffs (the highest in the Majors).
When you boil it down, it's just a 6-game losing streak. Lots of really really good teams have had losing streaks of 5 games or longer at some point within the season (the Giants last year had both a 5 and a 7-game losing streak on separate occasions). What makes this streak notable--honestly, the ONLY thing that makes it notable--is that it's to begin the season. Because long, 5+ game losing streaks are (1) generally rare to begin with and (2) even rarer to start the season (since a streak can start at any time besides the very last game, it's obviously rare to pick out ONLY the streaks that started on game #1 as opposed to any of games #2 through #161), it's just the case that not that many really good teams--like the Red Sox--have had them. This is why "only" 2 teams have ever made the playoffs after starting 0-5; the sample is ridiculously small and most of the teams who have started off 0-5 (or worse) aren't that good to begin with.
The Red Sox may not be as good as we all thought they'd be, but they're still really damn good and the best bet to come out of the AL East. If it's get to 10 or 12 then yea, I'd be worried. 0-6 is troubling, no doubt, and a pretty good indication that the Sox aren't the 98-to-100 win juggernaut they were expected to be, but I'd be shocked if they still don't win 92+ games as well as the AL East.