Assuming he can ramp up easily enough I would say Robertson, even after all this time off and at his age, is very plainly already better than those guys, and also better than Ross and Romano and possibly Banks too. Last year he was better than Kerkering too. From MLBTR:
a terrific 2024 season in Texas, where Robertson pitched 72 innings with a 3.00 ERA, a 33.4% strikeout rate, a 9.1% walk rate, two saves and 34 holds as the primary setup option to Kirby Yates.
It it admittedly skewed by the prorate and the overpay to outbid other teams, but Robertson is being paid almost twice as much $ as Alvarado or Romano [before the tax], and is also technically the third highest-paid reliever in MLB. He's our third or fourth-best reliever the minute he steps on the mound. His job and high-leverage role is poured cement unless he stinks like Romano.
I don't think they were ever going to get two more high end arms. It was gonna be like last year, one bigger guy and one modest guy. Possibly even just one guy and then relying on the starters. I think it's quite possible they don't trade for a reliever now, but they're definitely not trading for two.