The Jays were 14th in runs scored last year (7th in wRC+). You act like we were 25th. A simply return to a normal batting average with RISP would probably push us into the Top 10 in runs scored - even if there was little to no improvement from our core players. Minor bounce back seasons by Vlad, Springer, Kirk and Varsho and/or some breakouts by our prospects (Schneider, Horwitz, Barger, Orelvis) would help offset any other declines we may see (Turner, KK, Springer) and the loss of Chapman. Large bounce back seasons from those hitters and/or major breakouts for a prospect or 2 and we're probably a Top 5 offense.
I can appreciate what you're saying about the starters, but we do have more pitching depth this year than I can remember. A rebound season from Manoah alone would go a long way to covering any regression or injuries in the rotation. We also have Yariel Rodriguez, White, Francis, Ricky T and Chad Dallas to turn to if Manoah is finished and/or we have injuries. Now of course of Manoah is finished and 2 of our other starters need TJ surgery, we're f***ed - but so would almost every other team in baseball.