How to decide when you need a network engineer?

Hi all,

Have a question for everyone here. The short version is: How would you decide whether or not a company needs a network engineer?

The longer version:

We're a small finance company, ~200 users, ~20 offices, 3 datacenters (2 physical, 1 in Azure), ~500 endpoints including servers. IT team is currently 4 technical people + management, but we're in discussions on expanding that and trying to figure out which role would be best to hire for. We currently have:

1 analyst

1 help desk

1 systems/network admin who is much stronger on the systems side

1 systems/network/security engineer who is primarily security

None of our technical staff are what I'd call strong in networking (we understand subnetting/VLANs/ACLs and etc. But not OSPF, BGP, or other higher-level networking concepts). We're currently on an MPLS network for all of our locations managed by our ISP, and looking at moving to SDWAN for better bandwidth/cost savings/availability.

If you were in this position, what metrics/infrastructure/etc would you be looking at when deciding if a network engineer is the best use of budget vs outsourcing that function?

I'm sorry if the question is vague, or if I'm leaving out what would be considered key details in that conversation. I'm happy to answer questions or add details that would be useful.