Until the MOST recent Tamron 70-200 VC, the company's 70-200 f/2.8 lens was an utter DOG, focus-wise....it was unreliable on focus, and slow...a deadly duo of dubious deficiencies...
Sigma's 70-200 f/2.8 lenses of the early and mid-2000's were so crappy that they were basically, unusable for professional results until stopped down to f/4.
So...the guy's working on older information. But seriously...here's the 2008 dPreview review of the earlier Tamron model:
Tamron SP AF 70-200mm F2.8 Di LD IF Macro review Digital Photography Review the conclusion has these gems: "if we look solely at the studio optical tests, it is a resounding success, as the technical quality of the images this lens can produce is superb throughout most of the range, matching or even outperforming the much more expensive Canon 70-200mm F2.8 L IS USM. It's slightly soft wide open in the middle of the zoom range (most visibly on the more demanding APS-C/DX sensor format), but stop down a little and the quality really starts to shine through. "
And these gems: "The big problem with this lens, however, lies in the focusing systems. The autofocus motor is relatively slow and noisy, which puts it at a major disadvantage compared to its ultrasonic motor-equipped competitors, simply because AF performance impacts strongly on many of the typical uses for a fast telezoom lens. The slow speed of the motor means focus tracking simply isn't fast enough for sports or action, or even children running around playing; it's also a distinct problem in low light or with low-contrast subjects, where the lens can take what feels like an eternity to achieve focus. This is compounded by the noise the motor makes, which could be a real problem in situations such as wedding or event photography for which the user wishes to remain unobtrusive; discrete it is not. Also the Tamron lacks a focus limiter switch, so has a tendency to hunt back and forwards through its entire range when it fails to lock focus first time. But perhaps the biggest problem we encountered was a tendency for the lens to mis-focus, seemingly at random and disturbingly frequently, such that F2.8 shots in particular were often not critically sharp"
"So ultimately what we have here is a flawed gem, a lens which fully capable of delivering excellent images, but also frustratingly capable of missing focus on that once-in-a-lifetime shot, either through mis-focus or simply being too slow."
This is the kind of product that Tamron was offering not all that long ago...