Washington Nationals starting pitcher Dan Haren delivers a pitch during...

Washington Nationals starting pitcher Dan Haren delivers a pitch during a game against the Mets at Citi Field. (Sept. 11, 2013) Credit: Kathleen Malone-Van Dyke

As the Yankees and Mets begin looking for free agent values this offseason, here's a name to keep an eye on: Dan Haren.

Haren seemed to struggle with the Nationals last season, posting a 4.67 ERA and allowing 28 home runs in 169.2 innings.

But appearances are deceiving.

After all, there’s a big divide in the numbers between Haren’s first 15 starts and his final 15, particularly when it comes to those pesky home runs.

After a start against Colorado on June 22, Haren had a 6.15 ERA. He’d allowed 105 hits, 44 of which had gone for extra-bases, including 19 home runs. His .333 batting average on balls in play was slightly high, but nothing outrageous.

But then something clicked for Haren. He posted a 3.32 ERA during his last 15 starts, allowing 73 hits, 23 of which went for extra-bases. Only nine more balls left the park. His BABIP was at .278 during the period, this time a little low, but again, nothing outrageous. More of a market correction than anything else.

The biggest difference between the halves of Haren’s season was the amount of extra-base hits, particularly home runs, he permitted. Batters had a .548 slugging percentage and .242 isolated power during his first 15 starts. That decreased to a .355 slugging percentage and .127 isolated power during his last 15.

To illustrate that point, that’s like turning opposing hitters from National League MVP candidate Paul Goldschmidt (.551 SLG, .249 ISO) into the older, near-retirement version of Paul Konero (.355 SLG, .111 ISO).

So how did Haren make the adjustment?

There are a couple theories.

For one thing, Haren decreased his percentage of fly balls from 44.4 percent during the first half of his season to 38.9 percent during the second half. A lower amount of fly balls means fewer opportunities for those fly balls to turn into home runs.

But the far more interesting theory is that Haren didn’t click with catcher Kurt Suzuki.

Consider this: Haren had a 6.29 ERA and allowed 17 of his home runs with Suzuki behind the plate (11 games). When Wilson Ramos was the backstop, Haren had a 3.36 ERA and gave up eight home runs (17 games).

Haren’s turnaround also coincides with Ramos becoming his primary catcher.

During his first 15 starts, Suzuki caught Haren 10 times. Haren had a 6.83 ERA and gave up 16 home runs in those games against teams with a combined .490 winning percentage. During the four starts Ramos caught, against teams with a combined .530 winning percentage (White Sox, Dodgers, Tigers and Braves), Haren had a 3.46 ERA and allowed two home runs, turning in some of the best outings of his forgettable first half.

Ramos caught 13 of Haren’s final 15 starts, during which Haren gave up six home runs. Suzuki caught one (with Haren allowing one homer) before he was traded to the Athletics in late August.

*(If you notice those numbers don’t quite work out, you’re not wrong – and you get extra points for paying attention. Jhonatan Solano also caught two of Haren’s starts. Haren allowed three home runs during those games.)

This wouldn't be the first time Haren didn't work well with Suzuki. The two were teammates in 2007 with Oakland. Haren had a 2.33 ERA with a .329 opponents slugging percentage in 20 games (135.1 innings) with Jason Kendall behind the plate. He had a 4.23 ERA and .485 opponents slugging perentage in 14 games (87.1 innings) with Suzuki as the backstop.

Haren has worked with seven catchers for at least 100 innings during his career. He doesn't have an ERA higher than 3.74 with any of them -- except Suzuki, with whom he's at a bloated 5.05 ERA.

The catcher conundrum could help explain why Haren posted his normally excellent control numbers and yet was unable to keep the ball in the park during the first half.

Among pitchers with at least 150 innings pitched in 2013, Haren’s 4.87 strikeout to walk ratio was sixth-best, between Cy Young Award contenders Felix Hernandez (4.70) and Chris Sale (4.91). Haren’s 1.64 walks per nine innings was eight-best in MLB.

Despite a 4.67 ERA, Haren’s xFIP was 3.67. An advanced statistic that measures a pitcher’s controllable statistics while normalizing home runs, xFIP paints Haren in a far better light, next to pitchers like Justin Verlander (3.67), Derek Holland (3.68), Ervin Santana (3.69) and James Shields (3.72).

If the Yankees or Mets decide to go hunting for a bargain again, Haren could be just the guy to give them a great return.

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