Better pitcher to trade for?

ERA is huge? That's an odd formula... you would think WHIP would be more valuable.

Braden will be most expensive, but he's the better option. Oakland has the best defense of the trio, and a more reliable bullpen (helps with wins). Plus, he's young and offers more upside than the other two.

Wolf would be next... he'll likely pitch the most innings of the 3, but his ERA will be higher than Braden and he may lose wins to the Milwaukee bullpen.

I don't see Robertson as being worth making a trade for. Free agent, maybe... but not trading for, especially in a league that heavily rewards ERA (Robertson has only had an ERA below 4.48 once in his entire career, and he's had an ERA 4.90 or higher in 4 of his 7 seasons as a starter... plus, every one of his 5 seasons with more than 25 starts has ended with 10+ losses).

Dallas Braden because he has the best ERA out of those 3. Also, Dallas has the most Innings Pitched, and currently the Athletics have the same record as the Marlins and a better record than the Brewers. Dallas also has upside and is going to improve over the season because he has the easiest remaining schedule out of these 3 pitchers. Wolf is definitely worse than last year and has faced easy opponents (Houston, Washington, San Diego has a bad offense, and PITTSBURGH PIRATES 3 TIMES.) Nate Robertson has gotten lucky because it is his first year in the NL and the National League hitters and coaches will figure him out soon (especially NL rivals like the Phillies and Braves.) Dallas Braden is also the best for keeper leagues. Dallas Braden is your man.

I'd rank them...

Braden, Wolf, Robertson

Braden.