Isiah Thomas quick to get in stride on the pro court

''During the two years I played college basketball at Indiana, I could get any shot I wanted,'' explained Isiah Thomas, the rookie All-Star guard of the Detroit Pistons. ''With no 24-second clock to worry about, all I needed was a little patience and something good would invariably open up for me inside.''

''But in pro basketball those kind of situations simply don't exist,'' Isiah continued. ''You have to start looking for your shot much sooner and the defense is always more aggressive than anything you find in college.

''What still bothers me about my game as a pro is how dumb I am, even after half a season. Sometimes I don't think I've learned anything. For example, I'll go right back and try to put the ball up against an opponent who blocked my shot the first time down the floor. I won't even try to adjust, and then I wonder why it happened again.''

Even though Thomas, who led Indiana to the NCAA championship last season as a sophomore, may not sound all that high on himself, others are. He has given the fans in Detroit something they haven't had in a long time - a winning effort by a player who cares. He has already won several games for the Pistons with his last-minute heroics, and his defense is well above the garden variety played by most first-year pros.

For anyone wanting to put a yardstick on Thomas, one of the first things to remember is that he is only 20 years old. There is nothing about his lean sports car frame, either, that makes him stand out as physically indestructible. Yet sometimes, when his timing and range blend together, he sinks baskets with the rapidity and ease of a man tearing paper towels off a roll.

''It is definitely unusual when a rookie comes into this league and shows so much poise, the way Thomas has,'' said Don Chaney, Detroit's assistant coach. ''Isiah underrates himself when he calls attention to his mistakes, because he actually plays like a pro who has been around three or four years. I think he just forgets sometimes that even veteran players goof up once in a while.''

''One of the things I like best about Thomas is that his offense, which is very mobile, creates openings for other players,'' Chaney added. ''He takes the shot when it's there, and when it isn't he seems to know instinctively when to make the right decision and pass off.

''Isiah had some problems on defense his first time around the league because he was still learning his opponent's strengths and weaknesses. But now that he has seen everybody at least once, he knows what adjustments he has to make and he's made them.''

The other side of Thomas is his concern for people - his life away from the basketball court. He plans to go back to college every summer, even if it takes seven years to get a degree in criminal justice.

''I grew up in a heavily populated area in which there was considerable crime ,'' Thomas said. ''I saw a lot of poor people go to jail who I didn't think belonged there. Too often the punishment outweighed the crime and only made things worse for the individual involved.

''Most of the people I knew who got into trouble were kids who stole to survive. I mean they stole food for themselves and others because their parents didn't provide for them and they were hungry. I'm not saying crime is right, but often conditions have everything to do with why a young person gets into trouble. I had a problem that way myself one time, only it got settled in a different way.

''Right now I don't have many answers to the problems I've talked about. But there have to be more positive and more constructive ways to deal with people who steal only because they are hungry than the law has shown so far. I hope someday that I'll have the opportunity to work with kids who are first offenders and that I'll be able to straighten them out.''

As for the National Basketball Association season itself, Thomas says it has been much tougher physically and much more tiring than he thought it would be.

''I'm not used to this kind of travel, where you're in one city one day and 2 ,000 miles away the next, constantly flying across time zones,'' Isiah explained. ''I haven't seen much of any NBA city except Detroit, because usually I'm so drained physically that I spend most of my free time resting in hotel rooms. But I hope by next season that I will have adjusted more to this kind of travel and that I'll be able to make more constructive use of my time.''