In my experience, if the 57 and the "B" arrive at Packard's corner simultaneously, the "B" gets to move first and the 57 follows, according to the light cycle. At that point, there are only two scenarios under which the 57 loses the race to Kenmore: heavy traffic, or unusually long dwell times. And typically the 57 gets to Kenmore with enough time to go downstairs and catch the "B", despite Kenmore bus station's awful design.
But yes, it is due to the bad placement of stops and lack of signal priority on the "B". If those were improved, through stop consolidation or elimination, then the "B" would win more consistently. Although, the 57 has a similar density of stops (this is being addressed in the improvement program) but can usually skip more.
I don't know if the "A" was a better economic "stimulater" than the bus, since we can't re-run the first half of the 20th century in an experiment. But I just think that since 1970 there hasn't been any significant difference in economic development between Brighton along Comm Ave and Brighton Center/Oak Square that can be attributed to "having a trolley" vs not.
