Adding a proven starter will give them the most value this year for the roster. There are some hitters who would be upgrades right now but they would limit someone's playing time and potentially become a detriment in the future. A starter could decline as well but if Skubal does leave, it would be easier to add a starter now and another next year. If they are forced to replace the value of Skubal, Mize and Flaherty all in the same offseason, that is very difficult to do.