"can a security team have a higher level of maturity than the IT team that handles its operational tasks?"
It's an interesting question, and one that certainly requires some level of thought. My top-of-my-head response was - well ... no. This is clearly a "lowest common denominator" problem.
It should be rather obvious that a weak foundation cannot support a tall, strong structure. You simply don't have the stuff it takes to hold it all up, from a building perspective.
In the IT world, if you have weak operational IT practices, you'll never get anything better than weak security practices. For example, let's look at how IT views and assesses assets on the corporate network. If IT can't tell you every asset on the corporate network right now in an on-demand manner, with troves of accurate meta-data then you can't possibly expect to build a strong security operations program on top of that. Security needs foundational things such as the ability to know what's on the network and loads of meta-data about each asset in order to make decisions on the risks these assets pose.
Decomposing that even further to the most simple blocks - if IT doesn't know what's most critical to the business in terms of supporting function, security has absolutely zero chance of successfully crafting a defensive response strategy or operational plan. If an asset is suspected of being malicious or compromised (an IP address, for example) meta-data is needed to decide whether the alert could potentially be a false-positive, or if it even warrants a response (maybe it's just some lab machine which can simply be turned off). As a kid G.I. Joe taught us that knowing was half the battle - and not knowing means you're lost.
In an effort to try to understand this more, my line of thinking leads me to believe that organizations with a particular CMMI score when it comes to general IT, can only support an n-1 CMMI score for security maturity.
The reason I believe this is that security operations, by their very nature, cross many IT silos and require well-thought-out and precisely executed workflows and communication to function well. When you cross team boundaries, silos and responsibilities these inherently break down even a little - thus diminishing what you can build on top of them. Like the great pyramids - the higher you build the more you have to stack inward. Security - at least in my narrow view - is sitting right at the top of the IT ladder, thus making it fairly difficult to do well if the base of the IT operations is shaky.
The long and short of it is this - if your enterprise has poor IT hygiene, and ranks low on the CMMI scale - focus security effort and resources on helping IT level up before you start to drop in expensive and complicated security kit. In essence, flashy boxes or solutions won't do you much good when you try to operationalize them on top of poorly functioning IT infrastructure, processes and methodologies.