DETROIT — Zack Wheeler closed the book on an emphatic first half when he left the mound with 10 strikeouts and six scoreless innings behind him Sunday.Whether Wheeler should or shouldn’t be an All-Star, whether he should or shouldn’t go — that has already been dissected. What is apparent after the first half, however, is just how much he’s meant to this resurgent Phillies team.Just as the sky fell in April, Wheeler returned. Now he is 10-1 in 15 starts with a 2.13 ERA in 93 innings. The Phillies have won 14 of those games. Wheeler said Saturday he does not want a “pity party” about what he went through last year, when he was diagnosed with a blood clot and underwent thoracic outlet decompression surgery. But what he has accomplished since then has been simply incredible — particularly given, five months ago, no one knew what he might look like this season. Every time Wheeler is on the mound, the Phillies have a strong chance of winning — the kind of consistency they longed for during a disastrous first month.“He’s a tremendous pitcher,” Cristopher Sánchez said via interpreter Diego D’Aniello, “and one of the best pitchers in the league from seven years back. He’s one of the best to do it.”Perhaps that just sounds like praise from one teammate to another, from a teammate who has long admired Wheeler. But the stability the Phillies have gained by having Wheeler and Sánchez, the National League All-Star starter, lead their rotation has been invaluable for a team working through offensive woes and crawling its way back from a significant deficit. The Phillies have won 27 of 35 of their aces’ starts.What Sánchez and Wheeler have accomplished at the top of the rotation does not negate the Phillies’ thin pitching depth and problems from the fifth starter spot, but they are perhaps the most meaningful players in the first half, anchoring the staff and setting the table for a turnaround.The Phillies have gone from 9-19 and 10 1/2 games back of the Atlanta Braves in late April, when they fired manager Rob Thomson and elevated Don Mattingly, to 54-43 and two games back in the division as they enter the All-Star break. It’s a remarkable 45-24 (.652) resurgence over that span.Fittingly, Wheeler was on the mound Sunday as the Phillies punctuated that first-half turnaround with a 5-0 win over the Tigers, heading home for the break on a high note. There are still plenty of questions about these Phillies, but with a one-two punch of Sánchez and Wheeler, they know anything is possible.An outfield assessmentAn annual tradition continues: The trade deadline approaches, and the Phillies will likely target an outfielder. Still, there have been some pleasant surprises in the outfield this season.Brandon Marsh has broken out and will start in his first career All-Star Game on Tuesday. He was a sure thing when so much about this team was up in the air in April and May. He can hit lefties now. Rewind to February, and these facts would have been remarkable; they still are, even though his success is somewhat a continuation of the way he finished last season. His success, in part, has come from not being so hard on himself.“Maturity is a good word for — just learning more about myself, about who I’m facing, a lot to do with myself,” Marsh said last month. “I’m not trying to be Superman.”The second pleasant surprise is Justin Crawford, who has been better in recent weeks. Since June 1, he has been hitting .313/.340/.374 with a .714 OPS; it is not perfect, but better than his .565 OPS in May. Crawford has worked on shortening his swing, which he feels has fostered his improvement. And, beyond what’s happening at the plate, his defense in center field has been better than the first month of the season.Still, it will likely be another trade deadline seeking outfield reinforcements. Derek Hill has been a strong platoon addition, and Gabriel Rincones Jr. has looked a little better after a rough start. Will they both be on the roster a few weeks from now, though? It seems unlikely.ABS overviewDuring spring training, much was made of how valuable catcher J.T. Realmuto would be as the Automated Ball-Strike challenge system arrived in the big leagues. It was a fair assessment: More than halfway through the season, he has one of the league’s best challenge rates among catchers (79 percent) and a high net run value (1.5 more runs than expected by a player seeing identical pitches). But the longtime Phillies catcher lags in number of challenges. He has 39 of them (going 31-for-39), which ranks 35th among major-league catchers. Why?“To be honest, I’m probably just not quite as comfortable with it yet as I want to be,” he said. “I try to save them till late in the game. A lot of times, if we only have one challenge left, I don’t want to burn it in a spot early in the game without runners in scoring position or even early in the count, especially if it’s a close game.“We have pitchers in the back end like (Brad) Keller and (Jhoan) Duran, who have a lot of stuff and a lot of pitches get missed with them. So I always want to have one available if we have a lead late.”At times, Realmuto said he has pump-faked but ultimately didn’t challenge because of the in-game situation. He said he would like to be more aggressive in the second half.How much does all of this actually matter? The statistics around ABS are still evolving. But the Phillies rank in the plus category in total overturns versus expected (compared with teams’ fielders seeing identical pitches), which is obviously a positive. Phillies fielders have also eliminated 10 walks via ABS and added 13 strikeouts. They might just be one of the best teams in the league in these categories should Realmuto challenge more in the second half.