Forecasting what a player who has played the last three or four seasons in MLB is a fairly inexact science. We can get a decent idea of how good a player is based on his past record, weighting his most recent performance more heavily. We can also account for the player's age and try to account for the environment he's played in. Despite all that, there will always be players who over or under perform their forecasts in ways we just couldn't project.

It gets even harder when you try to project players who have spent the majority of their more recent time in the minor leagues. You have to estimate the strength of the leagues they've played in and also account for their ballpark. Fortunately, we have a lot of data points of players who have moved from the minors to the majors, and we can use that information to try and translate minor league performance to a rough major league equivalent. It's not perfect, but it's a decent starting point.

Harder still is dealing with players who will be playing in American organized baseball for the first time after playing in a different country like Cuba or Japan. The first problem is the small sample size of players who have made such a move. The more pressing problem is knowing whether they took advantage of specific environmental differences in their prior leagues – advantages that won't be available in the American major leagues.

For example, if a hitter has what's commonly known as a slider-speed bat played in a league where there are very few pitchers that throw over 90 mph he may dominate. In a different league where just about everyone can exceed the 90 mph threshold they may be overmatched.

Jose Abreu and Masahiro Tanaka are two players who are likely to be drafted early in a lot of fantasy leagues who require this type of forecasting. Let's look at Abreu first.

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I can look up Abreu's statistics in Cuba and see that he hit .342/.426/.621 there with 184 homers in 2686 at bats. If you pro-rate his career numbers to a 550 AB season he would hit 38 homers and drive in 121 runs. If you only look at his performance since 2010 it's even more impressive, as it would translate to 59 homers and 163 RBI in a 550 AB season.

Obviously, we would expect Abreu to lose a significant amount of that production by moving to the majors. To estimate that, we can look at the MLB performance for other players who defected from Cuba compared to how they did in Cuba prior.

It's not a long list, but it includes players like Yuniesky Betancourt, Yoenis Cespedes, Yunel Escobar, Adeiny Hechavarria, Jose Iglesias, Leonys Martin, Juan Miranda, Kendrys Morales, Yasiel Puig, Alexei Ramirez, Henry Urrutia and Dayan Viciedo. They hit a collective .312/.386/.497 in Cuba and have hit a collective .267/.305/.413 in MLB. So they hit for around 86 percent of their Cuba average in MLB, had an OBP that was about 79 percent of their Cuba average in MLB and lost a bit of power above and beyond the drop in average. If we weigh each player based on their MLB playing time, we get a slightly harsher translation in average and power and a slightly better one translation for on-base percentage. If you apply those translations to Abreu and then regress him a bit to the league average first baseman, you get a neutral projection of around .275/.355/.475 with 26 homers . Since he will be playing half of his games at US Cellular, a park that has boosted homers by anywhere from 20-35 percent over the last few years, his estimated projection for 2014 as a White Sock is .278/.366/502 with 31 homers.

It may seem a bit aggressive to project a player who's never seen a regular season MLB pitch to be among the top home run hitters in the league, but the math seems to agree with it in this case.

Masahiro Tanaka presents another unique challenge. We have more data on Japanese pitchers who have moved to MLB, but how we use that data is important. A lot of the more successful pitchers who have moved from Japan to MLB have been relievers, and it's easier to be effective when you are only facing a few batters in an appearance and can concentrate on using your best pitches. You also can't just use a simple rate of conversion of Japanese stats to MLB stats because the run environment in Japan has not been consistent. In 2010 the average team scored 4.47 runs per game in Japan's Pacific League. A new ball was introduced in 2011 that dropped that number to 3.41 and 3.37 in 2011 and 2012. In fact, the offense dropped so much that a livelier ball was secretly introduced in 2013 which boosted run scoring back up to 4.02 per game.

Rather than using straight translations to forecast Tanaka, I looked at the rates relative to the league in their last three seasons in Japan and first three seasons in MLB for the following starters. Yu Darvish, Kei Igawa, Hisahi Iwakuma, Hiroki Kuroda and Daisuke Matsuzaka.

Darvish allowed runs at about 50.4 percent of his league's average, allowed home runs at a rate of 40.3 percent, had a walk rate of 72.6 percent relative to his league, and had a strike out rate of 152.8 percent. Tanaka is the only player close to him, allowing runs at a rate of 51.4 percent. Tanaka was worse than Darvish in home run rate (50.9 percent) and strikeout rate (144.7 percent), but exhibited better control (45.3 percent). In MLB, Darvish has allowed runs at a rate of 81 percent relative to the league, has a home run rate against of 87 percent relative to league, has a walk rate of 128 percent relative to the league and has a strikeout rate of 152 percent relative to league.

Darvish is only one data point and has a different arsenal of pitches than Tanaka. But he's the most recent example, and the player who performed most similarly to Tanaka in Japan. But we never want to restrict our data to one sample point if we can avoid it, so to forecast Tanaka I used the average of the change in rates relative to league for the aforementioned starting pitchers. My primary concerns with Tanaka would be the infield defense behind him, the park he will be playing half his games in, and whether his excellent control in Japan was due to not being afraid to pound the strike zone against hitters who wouldn't punish mistakes the way MLB hitters will. There will also be the transition to working with less rest between starts. His projection is adjusted for the defense behind him and for Yankee Stadium's home run boosting effect. We'll have to see how his command translates.

The numbers say he should be a pretty good pitcher, maybe one of the top 15 pitchers in the American League. But expecting better than that in 2014 might be wishful thinking.

It's a risk to draft either Abreu or Tanaka early in any fantasy draft, but it may be a calculated risk worth taking.