The Toronto Raptors have officially inked Dwane Casey to a three-year contract extension to stay on as their head coach. First hired about a week after he won a championship with the Dallas Mavericks in 2011, Casey is the winningest head coach in franchise history and the team is coming off their deepest playoff run and winningest regular season ever.

Here's Toronto General Manager Masai Ujiri on why an extension was obvious (Raptors.com):

Dwane has done an excellent job leading our teams to success on the court and with helping us to develop a winning culture throughout our organization. Continuity is a part of establishing that culture. We are confident that with Dwane's leadership we will continue to grow our franchise.

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The most important word Ujiri says in his statement is "continuity." The Raptors have something that can't be purchased in free agency, swapped in with a trade or drafted with a lottery pick. They've established a respectable culture, on and off-court principles that define what they're about and how it affects where they're headed.

Players enjoy suiting up for Casey. Just about every member of the Raptors' core has grown and improved during his tenure, including Jonas Valanciunas, DeMar DeRozan and Kyle Lowry.

The team persevered through two elimination games, with various injuries and an oft-anemic offense. Some of that's on Casey, but his in-game decisions were solid, for the most part. Toronto punched way above its weight class in the Eastern Conference Finals and, facing a potentially-tumultuous offseason, need as much stability as they can manage.

Hiring a different head coach wouldn't inspire mutiny, but it would crack the very foundation Ujiri is trying to build. Casey was extended because every other option was shortsighted.