Sanderson is the only one worth looking at - maybe even Bannister too.
However, I don't see a huge pressing reason to get rid of Sabes at this point unless you're planning for the playoffs and your potential adversaries are sporting mostly RH lineups? Put him on a max of 6 or 7 innings, avoid righties and turn it over to your adequate bullpen.
The league average ERA/WHIP is 4.28/1.38 respectively. But what's even more telling is that the standard deviation for ERA in your league is 0.37 Runs.
Basically 68.2% of the league's pitchers are operating between a 3.91 and a 4.65 ERA. That's .74 runs difference. Unless you hit pay dirt with Sanderson and he starts turning in numbers significantly better than a 3.91 ERA and a 1.29 WHIP, it wouldn't be worth it. The devil known is better than the devil unknown at this point - especially after you listed the candidates available for replacement.
All I'm saying is that the league conditions show tight groupings amongst all of the pitchers for the league. In order to be significantly better than Sabes - the replacement will need to be below the figures I just stated.
Now if Sabes salary is a burden and prevents you from making other necessary moves - then I'd look at dropping him- perhaps. But I don't think you need a whole lot. Looks like a good team-just might have to ride the storm with your horses like what has already been suggested.
Just my 2 cents.