Masahiro Tanaka has been everything that the Yankees could have dreamed of since coming over from Japan. He has been the unquestioned ace of the staff so far, and is currently the only reliable starting pitcher the Yankees have.
Even without his best stuff in his last two starts, Tanaka kept the Yankees in the game and allowed them to win it. He has made hitters look foolish once they have gotten to two strikes with his nasty splitter. Tanaka is 4-0 with a 2.53 ERA and 10.76 strikeouts per nine innings.
However, Tanaka has given up far too many home runs this season, which is something that could get him in trouble if he does not correct it. Tanaka has allowed seven home runs in his six starts this season and has an incredibly high 21.9 percent HR/FB ratio.
Since Tanaka has walked so few batters, the home runs have not hurt him too much. Six out of the seven home runs have been solo shots. Since he is around the plate so often this could be an explanation for all the homers.
The strange thing about the amount of home runs that Tanaka has given up is that he has been a heavy ground ball pitcher this season. He has a 49.5 percent ground ball percentage compared to a 29.9 percent fly ball rate. This means that bad luck could be in play here.
I looked at all of Tanaka's home runs on Brooks Baseball. Five of the seven home runs that Tanaka has allowed on the season have been fastballs. The only breaking pitches were a splitter up and in to Melky Cabrera and a hanging slider up in the middle of the plate to Jonathan Schoop.
Six of the seven home runs I would categorize as bad locations. The only exception was a fastball that was in off the plate that Will Myers hit out of the park on Saturday.
Brooks Baseball categorized three pitches as four seam fastballs and two as sinkers out of the five fastballs Tanka has given up homers on. He left two fastballs up and in the middle to David Freese and Desmond Jennings. Also, Tanaka left a sinker up and away to Mike Napoli and one down and in right in David Ortiz' wheelhouse.
So, Tanaka's poor fastball location has seemed to be the reason for his home run troubles thus far. Fangraphs backs that up, as they have Tanaka's fastball worth four runs below average so far this season. He has made up for that with his splitter being worth five runs above average and his slider 3.9 runs above average.
Tanaka's fourseam fastball velocity has averaged 93.37 MPH this season. That velocity combined with the deception of his splitter and slider gives him an incredible repertoire. You would think that he would get away with more fastball mistakes, but that has not been the case. Tanaka's fourseam fastball is very straight, which could be another reason for the problem.
The Yankees will need to continue to rely on Tanaka until Michael Pineda returns and the offense starts hitting. The only two games the Yankees have won out of their last seven have been the two that Tanaka has started. It truly has been Tanaka and pray for rain.
Since this is still a small sample size --and Tanaka has a good ground ball rate-- this could be a fluke. Either way, it is something the should be watched for with Tanaka over the rest of the season.