Compared to last year's game, NBA2k15 presents a much tougher challenge from the computer A.I. I've typically played on all-star/superstar levels, but switched to playing on pro level w/sliders this year. My slider set of choice has been Armor & Swords "Average Joe" slider set. It is a good base set to use, and I recommend checking it out.
Armor/Swords "Average Joe Sliders"
In addition to sliders, here are a couple of tips that will help you improve your NBA2k15 skills...
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Complete 2kU Drills - If you have already played a couple of games, you probably have a good grip on game's basic controls. Completing the training drills in 2kU will help you learn the advanced controls and improve your overall skillset in NBA2k15. Also, going into practice mode and learning each player's shot on your team helps as well.
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Game Plan - This may be the most basic concept, but planning out your method of attack goes a long way in this game. If you have a team full of big players going up against a smaller squad, grind out post plays and use size to your advantage. If you have an uptempo team, push the ball up the court and turn the game into a track meet. Planning out a method of attack and having a gameplan for each game is huge in NBA2k15. If you are playing a season, be sure to gameplan for each game and utilize the in-game strategy features during timeouts to adjust to how the AI is playing against you.
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Patience / Running Plays - While playing NBA2k15, I have noticed patience is a virtue in this game. This is a simulation game, so running up and down the court jacking up open J's won't be the most successful plan of attack. When you bring the ball up the court, run plays out of your team's playbook, move the ball around and take good shots. It sounds elementary, but if you force yourself to complete 4-5 passes each time up the floor, you will find better shots and get better drives to the basket.
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YouTube / Online Streaming - If you go on YouTube, there are videos where people outline gameplay strategies for NBA2k15. Also, many OS forum members stream their games online. Check out some of these online streams as watching other people play this game will help you learn the game better as well.