IT says he's 5'9" no idea how he became a legit 5'10"?
He became a legit 5'10 by measuring 5'10.25 at the NBA draft combine. You know, the one time they actually put you on a scale and use a ruler to produce a definitive, reliable number.
In case this is not enough, Thomas has also measured between 5'10.25 and 5'11 on three other occasions in his draft year (2011) -- although these are perhaps less reliable. Overall, not really a controversial topic, as far as I am concerned. He's likely at least 5'10 in shoes, perhaps taller, depending on make and model.
This really isn't a big deal, just pointing out (again) that the 5'7 Isaiah Thomas is somewhat of a mythical creature.