Clearly a defective design!
And more purty
(base swing timer)(%attackspeed)(%agility) = real attack speed
Speed capped at 400% bonus, so the base swing timer matters a lot here. For example, you might think Clinkz fires quickly, he sure looks like it, but his attack speed caps at .34, or THREE (!) attacks per second. Alchemist ultimate reduces his BASE swing timer to 1.00, which not only makes attack speed that much more of an impact on his actual attack speed, his capped attack speed is .2, or an almighty FIVE (!!!!) attacks per second.
This is one of the reasons AM is a good carry. His attack modifier is relatively below average compared to other carry heroes, but his swing timer is well below theirs, causing him to attack much, much faster, even given the same agility and %speed from items.
By comparison, most (big majority here) heroes are 1.7 base swing timer. AM is 1.45, Alch ulted is 1.00.