One of the biggest challenges for IT leaders and their teams is that when they are the most successful, nothing happens. Systems don't go down, people don't have technical issues, your backup doesn't fail when you need it, you don't get a ransomware attack or a data breach, productivity isn't hampered by some ancient application someone won't let go of. Everything is fine. Nothing to see here.
Then, when all that doesn't happen, your boss or client tells you that everything runs smoothly and you can probably cut some of your budget, reduce staff, delay some refreshes or other projects. If you're an MSP, you might be having the "Just what are we paying you for anyway?" conversation.
In other words, someone comes in and tells you how to do your job when you're already doing it well, because it's difficult to attach success metrics to things that don't happen. Success leads to cuts, cuts lead to incidents, incidents lead to blame, someone gets fired, and someone new comes in to start the cycle over again.
If you're a leader coming into a new role, or an MSP coming into a new client, it's important to get a baseline. Measure everything you can, from service statistics to the technical state of the environment. MSPs should have the tools to do that easily. If you're in a corporate IT role you may not, and if you don't, that should be job one.
Once you have a baseline, document the trends improving over time. Now you'll know that what you're doing is working and bringing value to the business. You will also be able to demonstrate that value when the inevitable conversation happens. For an MSP this is easier, because people don't change providers when everything is going well, so you already know it's going badly. That may not be the case in a corporate role, but you do often find skeletons in the closet when there's a change in IT leadership.