Year  Home Runs 

2004

6

2005

2

2006

5

2007

5

2008

0

2009

6

2010

3

2011

4

2013

1

2014

8

2008 was an injuryshortened year and he missed all of the 2012 season also due to injury. There are a couple of 6's and 5's in there, so he has come close to this pace in the past to start the year. It's worth noting that Martinez was still was catching often through the 2010 season, so the grind of catching could have slowed down his pace in the past. However, even though he's mostly DHing now, he is much older, so it's still unlikely that he'll maintain his current pace. However, it's still fun to look at the numbers.
Year  HR%  HR/FB 

2004

3.9%

11.6%

2005

3.2%

13.4%

2006

2.5%

9.3%

2007

3.9%

13.2%

2008

0.7%

2.5%

2009

3.4%

12.5%

2010

3.7%

10.7%

2011

2.0%

7.3%

2013

2.1%

7.2%

2014

5.8%

17.0%

Career

2.7%

10.2%

The HR/FB ratios are taken from FanGraphs.
Martinez has hit 0.242 home runs/game, on pace for 39 home runs given 162 games.
Martinez has a 5.8% HR rate, on pace for 38 home runs given 650 plate appearances.
Martinez has a 17.0% HR/FB ratio, on pace for 38 home runs given 221 fly balls*.
*VMart is on pace for about 221 fly balls in 2014. He has a 39.2% fly ball ratio, an 8.7% walk rate and only a 4.3% strikeout rate and 0 hit by pitches.
Batted Balls = plate appearances  walks  strikeouts  hit by pitches.
Martinez has hit 0.242 home runs/game, on pace for 39 home runs given 162 games.
Martinez has a 5.8% HR rate, on pace for 38 home runs given 650 plate appearances.
Martinez has a 17.0% HR/FB ratio, on pace for 38 home runs given 221 fly balls*.
*VMart is on pace for about 221 fly balls in 2014. He has a 39.2% fly ball ratio, an 8.7% walk rate and only a 4.3% strikeout rate and 0 hit by pitches.
Batted Balls = plate appearances  walks  strikeouts  hit by pitches.
Given 650 plate appearances, that's 57 walks and 28 strikeouts. That's 6505728 = 565 batted balls. 565 * 39.2% = 221 fly balls (rounded).
We can start here with the regression. VMart's strikeout rate is the lowest of his career. Over his prior 3 years (20102013), his strikeout rate was at 9.2% and careerwise it's at 10.7%. This year, it's less than half of that. His strikeouts have been trending downward, but it's unlikely it'll remain at his current low pace. Let's say he finishes the rest of the year at 8.5%. Given 650 plate appearances, that's (650138 = 512 * 8.5% = 44 more strikeouts for a grand total of 50.
Martinez' walk rate over his prior 3 years is at 7.8%. His career mark is at 9.3%. His current 8.7% rate is right in the middle. It's reasonable that he can keep this pace for the rest of the year, so I'm leaving this one alone.
Changing his strikeouts to 50 and keeping everything else equal, that's 543 batted balls (650 PA  57 walks  50 strikeouts). At his current pace of 39.2% fly ball ratio, that's 213 fly balls. At 17.0% HR/FB ratio, that drops down to 36 home runs.
What about his 39.2% fly ball ratio? Over his prior 3 years it is at 36.6% and his career mark is at 36.2%. While it's not glaringly higher, let's regress it to 36% anyway. 543 * 36% FB%= 195 fly balls * 17.0% HR/FB = 33 home runs.
Now the big regression of his HR/FB rate. Over his prior 3 years, it's at 8.4% and his career is at 10.2%. He spent his 2010 season with the Red Sox and while playing half his games in Fenway, it was at 10.7%. Over his last 2 years with the Tigers it was at 7.3% and 7.2%. Let's say he only accomplishes 7.5% HR/FB the rest of the season. He's currently at 47 fly balls, so 19547 = 148 * 7.5% HR/FB = 11 more home runs this year, or 19 total.
Victor Martinez has had a 2.6% home run rate over his prior 3 years, close to his 2.7% career mark. Over his last 2 years with the Tigers it's at 2.0% and 2.1%. Given 650 PA on the year or 512 more for this year: at 2.6% HR%, that's 13 more (21 total) and at 2.1% HR%, that's 11 more (19 total).
In my 2014 preseason prediction for Victor Martinez, I gave him 13 home runs. If I were redoing them, I would up it to an optimistic 20. VMart is enjoying a bit of a power surge right now, but it's very likely unsustainable.