Brynn Anderson/Associated Press

All is not lovely in the City of Brotherly Love.

The Philadelphia Phillies enter the second half of the MLB season at 47-43, in third place in the National League East behind the first-place Atlanta Braves and surging Washington Nationals.

It's easy to blame outfielder Bryce Harper, the Phils' gaudy offseason acquisition. But another expensive culprit is an even bigger issue.

Sure, Harper inked a record-breaking 13-year, $330 pact over the offseason and is hitting a mediocre .253 with 105 strikeouts in 90 games for the Phillies. The 26-year-old failed to make the National League All-Star team in his first campaign in Philadelphia. That's a bad look, to put it mildly.

However, at least Harper has clubbed 16 home runs, has a .370 on-base percentage and 2.0 WAR by FanGraphs' measure.

Instead, Citizens Bank Park's infamous boo birds should aim their ire at a different target: Jake Arrieta.

The right-hander signed a three-year, $75 million contract with the Phillies in March 2018. That season, he posted a 3.96 ERA in 172.2 innings. Not disastrous, but far from excellent.

So far in 2019, Arrieta owns a 4.67 ERA and even worse 5.07 FIP with 0.6 WAR. And that's merely the tip of the troubling iceberg.

Mark J. Terrill/Associated Press

After posting an average fastball velocity of 94.9 mph in his Cy Young Award-winning season with the Chicago Cubs in 2015—the apex of his career—Arrieta is throwing his average heater at 92.8 mph this season.

Here's how his hard-contact rate has changed in the same span: 22.1 percent (2015), 25.2 percent (2016), 29.4 percent (2017), 27.7 percent (2018), 36.7 percent (2019).

The 33-year-old is also battling bone spurs in his right (throwing) elbow.

"Physically, I'm not in a great spot," he told reporters on July 7.

On Wednesday, manager Gabe Kapler added: "He's having a harder time getting extended the way he normally does, especially on that curveball. This is limiting his ability to throw the ball where he wants to throw it."

So, Arrieta is underperforming and has injury concerns. But we aren't done yet.

In April, in front of reporters, Arrieta openly criticized Harper for arguing with the umpires and getting ejected. Fair or not, it was something that could have been handled behind closed doors without risking clubhouse discord.

More recently, in a July 6 game against the division-rival New York Mets, Arrieta gave up 11 hits and three hit-by-pitches in 4.1 innings in a 6-5 loss.

One of the players he plugged was Mets third baseman Todd Frazier, who took exception and apparently made comments to the umpires.

"[If] Frazier's not happy about it, he can come see me and I'll put a dent in his skull," Arrieta told reporters after the game. "He didn't say [anything] to me. Talking to the umpire. I'm 25 feet away. He wants to come out there, he can come out there."

Matt Slocum/Associated Press

A fine or some form of discipline from the league could be forthcoming. A pitcher threatening to dent a hitter's skull is no laughing matter.

It's sports. Emotions run high. Adrenaline rushes. But those sound an awful lot like the words of an exceedingly frustrated player.

Arrieta should be frustrated. The Phillies should be more frustrated.

Philadelphia's starting corps ranks 19th in the game with a 4.64 ERA. The Phillies may be forced to raid their farm system to make a trade-deadline splash and shore up their rotation, even with ace Aaron Nola getting his groove back.

Meanwhile, Arrieta is earning $25 million this season while he grossly underperforms and causes unneeded distractions.

Harper deserves his share of finger-wagging and, if the Phils fans insist, boos.

But Arrieta is giving the Phillies even less bang for their buck—and bringing the most discord to the City of Brotherly Love.

All statistics current as of Wednesday and courtesy of FanGraphs and Baseball Reference.