The biggest mistake the Rangers ever made was not building a stadium that had a removable roof. It is so uncomfortable out there with the heat of July and August, which is a big part of the time when baseball is the only real game in town, unless you count Jerrah's "pre season games."
I suspect Arlington is a much better location. It's part of why Jerrah is across the parking lot now. And btw, you might not have known that Arlington itself is now bigger than a few long time major league towns.
I'd think 49K is pretty average by MLB standards, especially for a big market team, which the Rangers absolutely are these days. Had they built a stadium with AC, they'd have attracted the best free agent talent, and not seen them leave nearly as much when their contracts ended. Tom Schieffer gets such local praise for his oversight in building the stadium, now more than 20 years ago, but even though it has a classic look, it was a stupid decision for the franchise long term. If it were air conditioned for the summer heat, and with a roof for the bad storms of April and May, they'd still sell out a lot. But both can make a ball park visit miserable. And the players wouldn't be worn down as they typically do in this park.
Still, baseball in the metroplex has been in Arlington for close to 50 years. I'd be very surprised for them to move to Dallas, especially downtown. I cannot imagine the kind of traffic you'd have to endure for a 7 p.m. game on weekdays.