Plenty of signs this summer seem to be nudging the San Diego Padres to sell ahead of the Aug. 3 trade deadline.Under rookie manager Craig Stammen, the Padres are 17-28 since May 19. They rank 30th in runs scored, 27th in starters’ ERA and starters’ innings, and 30th in most farm system rankings. FanGraphs puts their playoff odds at 13 percent.And yet, there are other factors pushing San Diego in the other direction.The Padres don’t have many players on their big-league roster who would bring back a significant return, and several of them have no-trade clauses. Manny Machado, Xander Bogaerts and Jake Cronenworth are well into their 30s. Amid a recent dip in fan enthusiasm, the revenue machine at Petco Park continues to depend on maintaining robust attendance and drawing spectators through the appeal of household names. And after all of that, the Padres are still within 4 1/2 games of the National League’s final wild-card spot — and keeping a close eye on other teams’ big-league trade candidates.Difficult decisions lie ahead as the deadline approaches. Let’s get to your questions.(Note: Questions have been lightly edited for clarity.)What kind of return could the Padres get if they trade Mason Miller? — David B.It wouldn’t be the level of return the Athletics got last summer for trading Miller and JP Sears to San Diego: The A’s prize in that deal, shortstop Leo De Vries, is widely considered one of the five best prospects in baseball. But any potential deal involving Miller, who’s under club control through 2029, could bring back a haul of young talent. The Padres, who desperately need controllable starting pitching, should at least listen to offers for a dominant closer who hasn’t pitched much in recent weeks.Still, it wouldn’t be easy getting fair value for Miller. More and more teams have become reluctant to surrender top prospects, including in trades for an elite reliever. (Padres president of baseball operations A.J. Preller has proven to be an exception.) Though there hasn’t been a perfect analogue over the past decade, here are a few deadline deals involving top relievers: