I'm not sure this is unique to Abreu or not, but you can look at traditional stats and see that he is pretty good, and you can look at advanced stats and convince yourself that he's not very good. The Sox have score 549 runs this year, and Jose has driven in 100 of them. That's 18.2% of the runs. The player with the next most RBIs is Moncada with 63. His WAR is 1.4. I'd argue that's low only because without him, the Sox would have had to rely on others to score those 100 runs. Without those 100 runs, the Sox would have lost more than they have...a lot more. Maybe it's more of a fact that Jose truly is more valuable to the Sox than he would be to another team. On the Twins, who seem to hit every baseball out of the park, they have no one with more than 86 RBIs. But they have 5 players with more RBIs than anyone else other than Jose. So, for a team like the Sox who struggle to score runs (and give up a shitload), a guy like Jose is really valuable.
So, all of my above ramblings lead to me believing that Jose is better than he's given credit for, due in large part to the team he plays for. Because the Sox give up so many runs and don't have a lot of offensive punch aside from a couple guys, someone who drives in nearly 20% of the team's runs is pretty damn important. How important would he be on a team team with Robert, Madrigal, a more improved Moncada, an improved Jimenez, and a more consistent Anderson? I'd argue he'd still be important, but he won't be the best hitter on the team and probably won't be driving in the most runs.
I still believe he's valuable to this team for a couple more years, especially considering he most likely won't cost a lot.