“The most wrenching scene to write so far was Jack [Nick Wechsler] saying goodbye to his dog because mine had recently died,” says Mike Kelley (center, with script supervisor Heather Harris and exec producer Sunil Nayar).

Following an uneven second season of ABC's Revenge, showrunner Mike Kelley has stepped down.

The executive producer of the network's primetime soap, a darling during its freshman season, had been with the series since it debuted to strong reviews and solid ratings in the fall of 2011. Its sophomore run has been greeted more tepidly by both measures. Current executive producer Sunil Nayar is expected to take over during the series’ anticipated third season.

“Mike Kelley created a distinctive series for our studio and network with tremendous passion and dedication," said ABC Studios Executive VP of Creative and Production Barry Jossen. "We wish him all the best as he moves on to his next television achievement.”

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Added Kelley: “In a difficult mutual decision between myself and ABC studios, the end of my current contract will mark my final season as showrunner for Revenge. Helming this series has been the ride of a lifetime, and my producing partner, Melissa Loy, and I will look back on our Revenge time with deep gratitude and respect for Emily [VanCamp] and Madeleine [Stowe] and the rest of the incredible cast, our heroic crew, the dedicated and imaginative producing and writing team, and the tireless post production department. I would also like to thank Paul Lee, his marketing team, and the creative executives at ABC and ABC studios for their profound support throughout this journey. I’m excited about finishing post production on the season two finale, which I hope will stand among the best episodes of the series thus far. Continued success to all.”

Though it started the 2012-13 season as one of the few sophomore series to actually improve in ratings, Revenge's current season is tracking shy of its freshman run after suffering a light dip after the winter hiatus. Upon moving from 10 p.m. on Wednesdays to ABC's 9 p.m. Sunday slot, Revenge is averaging a 2.3 rating with adults 18-49 in Live+Same Day viewership. That's a 12 percent dip, season-to-date. The show is down 10 percent in total viewers to 7.3 million viewers.

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DVR viewership has fallen by a smaller measure, with the current season averaging a 3.4 rating among adults 18-49 in Live+Seven Day returns. That makes it the 10th highest-rated drama on the broadcast networks. It's been a relatively steady Sunday performer for ABC, which has seen drops for the evening's anchor Once Upon a Time and continued troubles in the 10 p.m. hour. For its part, Once is widely viewed as a broader success for both the company and the Disney brand, and ABC is prepping a potential spinoff.

What's more, critics have been far less kind to the show in its sophomore year, with a recent Daily Beast headline reading, Revenge: What Went Wrong With ABC's Once Daring Thriller? Sources close to the show suggest writers involved have been posing the same question.

Kelley, a former producer on The O.C. who created CBS' brief but well-received 1960s-set drama Swingtown, had a blind script deal with ABC only two years ago when the network expressed interest in updating Alexandre Dumas' tale of vengeance The Count of Monte Cristo with a female protagonist. Nayar boarded Revenge at the start of its second season, having previously worked on ABC Studios' Body of Proof as well as CSI: Miami CBS' short-lived Three Rivers.