Why would a 37 year old player have a wOBA spike of over 50 points from one season to the next? This is the question people should be asking about Jason Varitek and his surprising start. This is a difficult question to answer because he is getting lucky and unlucky at the same time.
Let us start with the good. Jason is hitting and excellent 21% Line Drive rate and 36% Ground-ball rate.

These numbers should put his BABIP above .300 but his current is a meager .182. There is no conceivable way where he would hit for those rates and still fall under .250. In 2007, when his numbers were comparable, he managed a .318.
His plate discipline and pitch recognition has also improved upon last season. Jason has lowered the pitches he swings at outside of the strike zone by 4%.

Furthermore; the pitches he does swing at outside of the zone are making contact 14% more. Overall, he is swinging less and making contact at a much improved rate. If a player can sustain that, he will inevitably improve his numbers.
Now let’s discuss the lucky. If you look at what led to Jason’s poor season, the easiest way to explain it is in the pitches he saw. Before last season, he would see nearly double (about 8% to 16%) the change-ups verse curve-balls. The rates were never closer than 7% of each other in a given season.

Last season, the difference was just under 2%. He saw 4% more curve-balls and 3% less change-ups. This season is nearly identical to last season (CB%=11%, 11.4% and CH%=12.9, 13.4%).
It is difficult to be 100% about why pitchers stopped throwing change-ups and starting throwing curves to Jason. My best guess would be Jason’s inability to catch up to fastballs led to him having more success against the change. If someone has a better explanations please tell me, I’m honestly very curious about this.

That being said, I can be nearly 100% positive that his did negatively affect him. Assuming this is true; we should expect his numbers to begin to come back down to earth.
Another troubling fact about his start is his home-run to fly-ball rate. His career average is 13.8 which are pretty standard. This season, however, he has seen a spike up to 22.2%. He has not had his average in the 20’s since 2003. One would expect this number to come back down to earth and his home-run totals to do the same. It is possible that his power is up but not this much.
Finally, Jason is not a speed guy.

This is nothing new and blatantly obvious. Why it is then that infield hit rate of 13.3%? His career total is 3.8%. Unless Jason has stole Ricky Henderson’s legs, this number is not even close to sustainable, especially when you consider his infield fly-ball rate has not changed at all. When this number comes down, expect a decrease in his OBP.
So, what’s the conclusion? While pitchers have figured out how to beat Jason and he has got lucky with several indicators, there is still a good chance that he will sustain this production.

Sorry if this got a tad “stat heavy” but it was necessary to make a point. I said at the time this signing was a good one and I stick by it. Jason will be a top 15 catcher this season and well worth the money he received.