It might have seemed as if the Chicago Cubs would glide toward their first division win in five years, but the Milwaukee Brewers have since emerged as one of the best teams in the sport and have built up a sizable lead in the National League Central.

And while the Cubs are still enjoying a strong season, their slip in the standings has coincided with a troubling trend for the best player on the roster.

“Both the Cubs’ offense as a whole and Kyle Tucker individually were among the best in baseball for the first few months of the season,” Sahadev Sharma wrote for The Athletic. “Now, as the Cubs’ offense has struggled to live up to the incredible early standard it set, the spotlight has fallen on Chicago’s struggling star.”

After the Cubs landed Tucker in a surprising trade with the Houston Astros this past offseason, his hot start earned him a fourth consecutive All-Star appearance. But since the start of July, Tucker has logged only one homer and has fallen below the league average in Weighted Runs Created Plus (wRC+), an advanced measure of offensive production.

“Not great,” Tucker said of his recent slump, per Sharma.

Cubs manager Craig Counsell was a bit more positive though when asked about Tucker’s slump as concerns are starting to grow for the team’s offense as a whole.

“There’s a lot of good things happening there, it’s just he’s missing some pitches he feels like he should hit,” the manager said, according to Sharma. “That’s hitting sometimes. You miss a pitch you should hit, a pitcher makes a good pitch and you’re walking back to the dugout. That’s the fine line of hitting in the big leagues.”

Counsell is surely hoping that Tucker’s decline is merely a matter of the natural ebbs and flows of offensive production for all hitters. But with the playoffs rapidly approaching, Tucker will have to return to his early-season form soon if the Cubs want to carry more momentum toward a World Series berth.