There really is no stretch if you look at the data:
||Average 100% (min)
||Average any% (min)
You’ll note that on full completion (2nd column), Swann ranks 17th (as you indicated) but varies from the average of medians (Stukov 18.17 & Mengsk 19.19) 18.68 by only 1.75min or 1min 45sec. Similarly, for any%, Swann ranks 11th and varies from average of medians (Stetmann 16.07 & Fenix 16.19) 16.13 by only 1.28min or 1min 17sec.
This means for lower 50% performing COs of the 18 available, Swann's actual tested capabilities and speed varies less than 2min from 9 other COs. That difference comes about mostly 100%'s definition, which include 'bonus, perfect objective, full clear, etc.' That is not the average way most players operate in missions.
You need to understand that Swann performs perfectly fine. He’s build orders are harder to master than others, especially if in your mind one keeps comparing him with Abathur, Zeratul, etc. His DPS ramp up time is comparably insignificantly different from 50% of the COs. So your feelings of Swann is just a reflection of your own underperformance.
I am though… gonna be critical… er but fair. (Cuz otherwise, why make comments such as “Swann has a huuuuuuge ramp up”?)
The map was full cleared by ~15min, which if anyone paid attention is really done by his ally than by him. While he did a very good job at the beginning (prior to 5min) by not going gas heavy, his major mistake was going 2 x Armory research started then ==> 3 x Starport before making any units at all. His contribution to his ally is really just his P1 Drill’s Advantage. Now, I don’t think 3 Starports was a wrong choice, given how his game unfolded after 7min mark ish. The mistake was not building that up then adding 2nd Starport and perhaps a questionable 3rd Starport.
Now let’s step back for a second, he posted this in regards to portray why Swann has a slow ramp up.
And I think it is very clear why Swanna doesn't and why his Swann does. That is the very definition why a ramp is not a cliff.