NBA Stats Tracker is a basketball analysis tool. It allows you to add teams and players to a database and gather stats either by entering the box scores of each game, or by manually editing the stats yourself.
What the tool offers is deep analysis and comparison for every team and player, as well as league-wide overviews. It also features scouting reports in natural language which can help you prepare against an opponent you're unfamiliar with, get to know their strengths and weaknesses, as well as what trends come up out of their recent performances.
All analysis features can be applied to a season's stats, or any specific timeframe starting from days up to years.
Whenever you find yourself in a window that has a table with teams, players or box-scores in it, double-click on any of them to get to the overview screen of it.
Each database can keep data from multiple seasons. You can compare yearly averages, as well as compare results against a particular opponent over the years, for example.