I think this is a bit harsh on AC. Looking at the ranking posted above, it's in a pack with a whole bunch of others within 2-3%.

As for my own experience, the vast majority of my flights on AC this year have been a few minutes early.

It's interesting to me that AC ranks ahead of UA in OTP though, because in my experience, UA's block times are hugely padded. Take a look at YYC-IAH, where UA's block times are about 20 minutes more than AC's. It's not that 737s/320s fly slower than CRAs, it's padding. YYC-ORD on UA has longer block times than YYC-YYZ on AC even though it's almost 20% shorter. If a UA flight leaves the gate on time or close to it, I therefore find we're usually quite early to destination. Yet AC still does (very slightly) better.

I fly DL a lot less, but my experience there has been quite good, very few delays, but again, block times that seem very significantly padded.