The big news here is that they didn't sign a cornerback to replace CB Trevor Ford, who was recently promoted to the active roster. Despite the loss of CB Al Harris, the other recent signing of CB Josh Bell meant they didn't need another DB. There was a rumor about them bringing back CB Joe Porter, but apparently that came to nothing.
As for Crabtree, he's been on-and-off the Chiefs practice squad a couple times this season. Over at Arrowhead Pride, Joel Thorman came across impressed with Crabtree's performance in the Chiefs final preseason game. On the other hand, Crabtree was ranked 62 out of 88 TEs available in the 2009 NFL draft. But as you can probably learn from any draft bust, it doesn't matter as much how good you looked during the pre-draft workouts as how you play once you get to the NFL. He doesn't fill a need, and certainly won't make it onto the active roster this season, but it appears he has good hands and football smarts. He should make a nice addition to the practice squad.