[Troubleshooting Port-Mortem] 5 port old switch causing unrelated ports on a 2960 to drop 50%+ of outgoing packets?

Junior tech here, working for an MSP. At a client today, and was working on an issue with poor application performance. Noticed pings dropping like crazy from users desktops to the SQL and App servers.

Checked the 2960 they have in the main closet and after clearing counters and watching output drops for a bit, 8 ports were dropping 50, even 75%+ of outgoing traffic. I'll admit there were probably other stats I could have checked, but I found the MAC addresses of the users PC's who were complaining, and they all came up under one port. Assuming correctly, there was a switch buried between their desks. Old 5-port linksys 10/100.

Removed, swapped with a 5 port gig dumb switch, and when I checked the counters they sat at 0, and still sit at 0 for all ports.

Users across the company report way better performance for their applications. Is there a reason I'm not thinking off that the removal of a switch like this would fix? I doubt it was messing with STP, right?