It's generally misguided to critique the performance of bench players. If they were capable of solid performance, they would have regular jobs. Still, this, doesn't look like much to work with.
*wRC+ is a measure of the hitter's ability to produce runs compared to league average. A score of 100 would indicate that a player is 100% of the league average. A player who had a wRC+ of 120 would be 20% better than that league average. So, as you can see, all of these players are quite below. With Eduardo Escobar, he's performing so poorly as to produce result off of the scale.
Robin wants to keep all of his players fresh over the season, and play the matchups, and make sure every player is active and all that good stuff. But it doesn't appear as if he has a major league hitter available to him when he turns to his bench. Tyler Flowers is somewhat forgiven because he has the ability to squat behind a plate for nine innings, Fukudome has had bad luck on some line drives hit right at people. But Lillibridge and Escobar have both been wasted plate appearances so far. The infield has been the area most deserving of days off this season, but giving more opportunities to this pair of reserves--or 9th inning pinch-hit chances--is counter-productive.
While it's easy to surmise that Brent Lillibridge shouldn't be turned to for kickstarting rallies, how Ventura is supposed to manage a bench where everyone is poison is a mystery. He's shuffling a deck that's missing cards, as there just aren't enough players on the roster who can hit within 20% of the league average, and support a lineup that otherwise has a solid leadoff man and a dominant middle of the order.
The bullpen on the other hand, can probably be held to more scrutiny.
Ventura definitely needs to knock out the chances he gets to utilize his top bullpen talent (there's no reason besides injury for Sale and Reed to not be 1 and 2 on this list by the end of the year), because managing his offense is going to have a much higher degree of difficulty.The sad tale of Addison Reed being more protected from difficult situations than a rushed rookie without a breaking ball (Santiago) and a dyed-in-the-wool LOOGY (Ohman) is a less sympathetic plight. Now that Sale is to absorb the closer role entirely, it could get worse for Reed, as there will be less disasters for him to avert.