The team has 2 good hitters (Dunn and Zim), 1 above average hitter (Morse), 1 around average hitter (Desmond), 1 mediocre hitter (Bernadina), 3 crap hitters (Pudge, Morgan, and Espinosa), plus a bench filled with crap (Maxwell, Nieves, Harris, Mench). That is not a good lineup. With Hammer, it's a possible average lineup, but not with Bernadina as our #5 hitter and Morgan at leadoff.
Remember we're talking average, not good and I've excluded Morgan already. He can't even be in an average lineup.
I'm assuming we keep Dunn and that Willingham comes back healthy. And we don't know what kind of hitter Espinosa is yet. He doesn't even have to be particularly good to outperform the offense we've gotten from 2nd this season. We've gotten incredibly bad offense from the 2nd base position. AND I'm assuming we sign another bat, likely outfield.
The path to average is determined by who is our worst (relatively) hitter. I'm assuming that to be Bernadina at CF which means we'd also have to have better performance at catcher because we've also underperformed, offensively, at the catcher position this season but average performance at the catcher position is easier to achieve because catcher isn't a high offensive output position, generally. That means less Rodriguez and no Nieves.
We also would need a better bench. We've gotten below average performace from our bench but not as much below average as you'd think (I just checked the numbers). Again, our objective in this particular exercise is average, not good.