Sky Andercheck looks at the liklihood of a great pitcher throwing a scoreless inning by the run production of their opposing teams, and uses that to figure out the three most improbable scoreless innings streaks ever.
Predictably, Orel Hershiser's famous 1988 streak comes out in front, with Bulldog's chances of shutting out a team for a whole inning suring that run coming in at about 80%. Doing that 59 times in a row, though, comes out as a one in 485,000 chance.
The next two streaks are Walter Johnson's 55.2 straight innings in 1913 (one in 435,000) and Sal Maglie's 45 innings in 1950 (one in 419,000).
For a pitcher today, the streak would have to go about 45 innings to pass those three in difficulty. So Greinke was about seven innings away from having the most improbable scoreless innings streak ever. Nifty!