This is probably one of the simplest, easiest, and most convenient blues scale fingering patterns to use. Take a look at it and then take a look at the chord chart of an 'A' in the fifth fret barre position. Notice any similarities?
Well for starters the roots for both the chord and the scale are the same. Which means that just like the barre chord the scale can be moved up and down the fretbaord to change the key. So, say for example you wanted to play a little blues in the key of 'C' then all you would have to do is start your scale on the eighth fret position of the low E string. That is what makes this fingering position of the blues scale so convenient. It makes it easy to memorize your scale fingering pattern because it so closely resembles your barre chord shape. It is also very easy to find the blues scale in any key on the fretboard.