According to his father (and NBA Champion) Mychael, Klay Thompson was throwing up and complained of dizziness after Game 5 on Tuesday — the one where Klay got kneed in the head by Trevor Ariza. I’m no doctor, but those are classic signs of a concussion.

Finally on Friday the Warriors admitted what everyone else seemed to know — Thompson has a concussion. Here is the official statement:

Following extensive examinations over the last two days, including Neurological tests earlier this morning — Warriors’ guard Klay Thompson has been diagnosed with a concussion. He will not return to the court until he is symptom-free and cleared under the NBA’s concussion protocol guidelines. He will be evaluated daily, and there is no timetable for his return.

This a day after his agent said Thompson did not have a concussion.

This has to be about Thompson’s best interests — there is no such thing as a “mild” concussion. Bruising your brain is serious. Fortunately, the NBA has a pretty extensive concussion protocol once there is an official diagnosis of a concussion. Thompson will have to meet a neurological baseline on tests (established by tests he took when healthy) and do so during increasing levels of physical activity. This is all overseen by a league neurologist — it’s not the team doctors who will let him return to the court.

The good news for Thompson and the Warriors is the long break until Game 1 next Thursday. There is a reasonably good chance he will be cleared by then (based on the history of other players around the league).

The real question for the league going forward is the diagnosis of a concussion during games. Thompson never should have been cleared to return to the game in the first place, yet he was (and if he hadn’t had an ear laceration he likely would have been on the court). For one thing, concussion symptoms do not always manifest immediately, they can take time to show up. Also, this is diagnosed by team doctors — paid by the team — who are supposed to look out for the interest of the player but may not always see things through that prism (the NFL has had this issue).

The NBA needs to review this process going forward.