Having had the delightful good fortune of being the 'it manager' of a 300-ish person company I will tell you that when you have 3 people, there are no meaningful metrics. Work load is too elastic and with a 10k user company, there won't be enough context in which to evaluate any metrics anyhow.
The questions are instead answered with common sense :
- Do my people have good work ethic?
- Do our solutions work, and are we encouraging best practice?
- Do we do what the business needs, in time to meet the businesses goals?
- Are the people paying the bills happy?
And that's all you can do. Trying to evaluate SLAs, ticket closures, and other non-statistics won't produce anything meaningful.
For what it's worth, after 20 years of this business most of the stats I've seen from big businesses (100K + employees) were worthless at best and downright misleading at worst, where notoriously bad employees were actually able to game the system by cherry picking easy-close tickets, refusing to give their names when customers with hard issues called, hanging up on users, and not creating tickets when issues required followup to avoid having long ticket times. Those people end up getting rewarded, which demoralizes everyone and encourages defection.
Unfortunately, in an absence of common sense and connection to the work, management refuses to admit their lack of competence of judgement and would rather tout metrics as a serious tool.