So are there any definitions of "careless", "reckless" and "intentional"? Or are we expected to rely on the dictionary definitions?
Say you are going through a crowd of people. You accidentally walk into someone because you are texting. This seems careless to me. You did not take adequate steps to ensure it did not happen. You did not want it to happen and it didn't have to happen, but it did.
But if you run through the crowd at speed, dodging this way and that, hoping that there will always be a clear path, and all of a sudden there is nowhere to go and you run into someone - that seems reckless. There was always a chance it would happen, you could reasonably have expected it to happen, and sure enough it did.
Lastly, if you just decide to run into someone, and you do it - that seems intentional. It was what you wanted to happen, and it did.
So Buddy's hit was intentional. He did not suddenly find there was no way to avoid a collision. Rather, he suddenly decided that faced with the option of chasing the ball or laying a bump, he'd lay a bump.