You do not have to attempt to explain it, I have taken some statistics courses and I understand all the possible statistical explanations, however, one possible explanation is that Devon Travis does not provide the team improvement that his fWAR indicates. Afterall, the fWAR statistic is intended to do this. The Blue Jays are 10 games under .500 when Travis plays; if someone does not believe this then check for yourself. Perhaps once Travis has 1000 ABs the we will have a better picture as to whether his play helps the Blue Jays, is neutral or below average. For now, I am not convinced.
There is no doubt in my mind that if Donaldson were injured for an extended period of time, then the Blue Jays record would suffer. I believe this because Donaldson is better defensively than anyone else on the team at his position, and his hitting is also excellent. On the other hand, Travis' defense is not better than Goins defense so Travis' fWAR is not as meaningful when compared to Goins. Travis made one leaping play at 2B last night that the TV annoucers really played up (that is their job), but in reality any average infielder makes that play and some taller players can do it without even jumping. In Thursday's game at Chicago, Travis booted a ball to Goins that Goins turned into an out and saved Travis an error.
Baseball is just a game but one that I have enjoyed since the early 1970's when I started following the Expos. I was an Expos fan first and Blue Jays fan second but now I am only a Blue Jays fan. I saw the first game the Blue Jays ever played in 1977 on TV. I saw my first Blue Jays game at Exhibition Park in 1980 against Jim Palmer of the Orioles. I just think it is too bad that the Toronto team wasn't in the National League since it would have been better for the Expos. I also would enjoy watching the games more because I enjoy defense and offense equally (which is more important in the National League).
I think baseball appeals to people for the beauty of the game and also because of all the stats involved. However, the stats need to be considered with caution.