Northrop's track success goes back decades. Probably not much to do with open enrollment, but more about those leading the program. I think all city schools are blessed with speed, it just doesn't translate to the football or track fields without the right person leading the way.
I honestly can't tell you when open enrollment started in Fort Wayne. If I were to guess, I would say it's been around for a couple of decades. I believe each school is allotted x amount of transfers, but it has to be academically motivated. Each school has an academic program that is specific to that school, therefore giving students the opportunity to transfer to that school for academic purposes. Does it get abused? Probably. But probably not to the extent that people think it does.
Snider enjoys success because their coaches know how to develop players for the next level. They just do things differently than thier FWCS counterparts. Bishop Luers not only have good men leading the way, but they're also the recipient of many athletes on the voucher system. The Knights aren't 100% good ol' catholic kids like they were in the 80's and early 90's. Dwenger has always been good about developing through their pipeline (Dabo mentality). North Side is loaded with talent, but is at the mercy of who's leading the way at the time. Same with Wayne, Northrop, and South Side. Consistency is key, and Snider's had it for five decades now. They've built a community that spans over 50 years. That's the difference. If you look at major D1 football talent from Fort Wayne, you'll see that they come from just about every school district. I think Snider's just better at developing the DII and DIII kids.