American twins Bob and Mike Bryan find themselves in an unfamiliar spot entering 2016. The brothers finish 2015 without a Grand Slam title and ranked second in the final rankings. It is the first time they have not won a Grand Slam since 2004 and the first time in six years that they did not finish a season ranked number one. The question for 2016 will be if the 37-year-olds can regain the dominant form that saw them win 21 ATP Tour titles from 2013-2014 with four of those coming at Grand Slams or if 2015's less successful run is more indicative of their current level of play?

Win-Loss Record

By the numbers, a 44-16 record for most doubles teams would seem rock solid for a calendar year. By the lofty standards of the Bryan Brothers though, the 44 wins marked a significant decrease for the American twins over their normal numbers. Bob and Mike's dominant run in doubles over the years saw them win 60-plus matches per year from 2006 to 2014.  The 44 wins in 2015 was their lowest since 2005 when they won 58 matches. It is a 20 win different just from last season when the pair won 64 matches during the 2014 campaign. So although a 73 percent winning percentage is stellar, it is far and away their worst season in quite some time.

High Points

The Bryans still racked up six titles this season. That left both brothers tied with Marcelo Melo for the most men's doubles titles in 2015. The brothers won three ATP Masters 1000 level tournaments in Miami, Monte Carlo and most recently in Montreal at the Rogers Cup. The Rogers Cup win is likely their best moment of the season as they scored their 109th doubles title as a team and 35th Masters title of their careers. It also was the third leg of back-to-back-to-back titles during the summer run for the Bryans in Atlanta, Washington D.C. and Montreal. They defeated Daniel Nestor and Eduoard Roger-Vasselin in the Montreal final 7-6 (5), 3-6, 10-6 for their fifth overall Rogers Cup title.

Photo: The Canadian Press

Low Points

Low points for the Bryans came far too often this season, which led to their lower number of wins on the season. Some of that can be attributed to the twins failing to win a Grand Slam for the first time since 2004. The Bryans started out the Australian Open with a second consecutive third round exit as the brothers were ousted by Dominic Inglot and Florin Mergea 7-6 (4), 6-3. At the French Open, the brothers had a marvelous run to the final. The team of Ivan Dodig and Marcelo Melo edged the Americans 6-7 (5), 7-6 (5), 7-5 for the title. Wimbleon also featured disappointment as the Bryans lost in the quarterfinals to Rohan Bopanna and Florin Mergea 7-5, 4-6, 6-7 (9), 6-7 (5). The U.S. Open was likely their lowest moment. In search of their lone Grand Slam title of the season, the Americans were stunned in the opening round by fellow Americans Sam Querrey and Steve Johnson 6-7 (4), 7-5, 3-6.

Best Results

The Bryans best run in 2015 was during the summer hard court swing in North America. Bob and Mike started off winning the BB & T Atlanta Open over Colin Fleming and Gilles Muller 4-6, 7-6 (2), 10-4. They would make it two titles in two weeks as they won the Citi Open in Washington, D.C. There, the Bryans scored some revenge by crushing Dodig-Melo 6-4, 6-2 in the final. The twins would win the Rogers Cup men's doubles title the following week in Montreal over Nestor and Roger-Vasselin to make it three straight weeks with titles. It was easily their best run of the season.

Worst Results

Not winning a Grand Slam for the first time in eleven years is disappointing, but there was simply no bigger disappointment than their first round loss at the U.S. Open. First round losses for the Bryans are unicorns. The twins had lost just once in the opening round of a Grand Slam since 2001. That firs round exit also came at the U.S. Open back in 2011 against Ivo Karlovic and Frank Moser. This time around, it was a pair of power serving Americans who took them down. Steve Johnson and Sam Querrey were jut 5-9 as a team in 2015 prior to meeting the twins in Flushing Meadows. That included a four set loss to the Bryans at Wimbledon in the second round.

Photo: Getty Images

Grade: C+

Most teams would consider winning six titles in a season, half of which were at Masters events, a solid year. For the Bryans, their unbelievable career has left that number looking small. Their six titles in 2015 were their lowest since winning eight in 2008. The bigger failure for the season was their inability to add to their record 16 men's doubles Grand Slam titles. Two early exits at the Australian Open and U.S. Open really stung this remarkably consistent duo. The Bryans will start 2016 as the hunters for once as they chase the newly crowned number one team of  Jean-Julien Rojer and Horia Tecau. A good start for the twins would be recapturing success at the Australian Open in January. They have won six of their 16 career Grand Slam titles in Melbourne.