Giants fans have been subjected to a lot of uncertainty in recent months. 

Their cleanup-hitting catcher is recovering from a season-ending injury suffered last year. Can the team find enough offense from this group of prospects and retreads to back up Ryan Vogelsong, a mid-thirties veteran who essentially had the first decent year of his career last year?

Combine these things with a new surgery for Brian Wilson and a decent opening week by Barry Zito, and the San Francisco faithful can be excused for not knowing which way is up.

And to add fuel to the flame, long-time ace and resident strikeout king Tim Lincecum is right now the team’s worst starter.

In this young season, Big Time Timmy Jim has compiled a 12.91 ERA while allowing 2.217 base runners per inning, all in just 7.2 innings over two starts. Wednesday in Colorado, Lincecum had the shortest start of his career, giving up six runs in only 2.1 innings.

Needless to say, the Bay Area is on the verge of growing restless. Is there reason to be worried?

The big concern so far is obviously the velocity on Lincecum’s fastball. In 2008, the year in which he won his first Cy Young award, his heater averaged 94 mph. Last year, that number was down to 92.2 mph. And in his season opener this year, his fastball was all the way down to 90.0. Obviously, something’s wrong.

Now, as we all know, velocity isn’t everything, it’s how you use it (at least that’s what they keep telling me). Lincecum’s strikeouts, the bread and butter of his effectiveness, have largely been due to the contrast between his fastball and his change-up. Whereas in years past the difference in velocity between the two pitches was about 9 mph, according to Fangraphs that difference is down to 7 mph so far this year.

So he could still be successful throwing 90 mph, but he’ll have to adjust his change-up accordingly, or introduce more movement to his repertoire.

Unfortunately, over the past couple years, Timmy’s strikeouts, and therefore his effectiveness, have become just a little harder to come by. Between 2008 and 2010, LIncecum led the National League in both total strikeouts and strikeouts per nine innings pitched, although in truth 2010 was significantly less impressive than the previous two years.

As his velocity has dropped, so have the strikeout totals. He struck out just 9.1 batters per nine innings last year, which is still really good for your average pitcher, but for Timmy it’s a career low, down from 10.5 in ’08. To add insult to injury, he’s walked more batters over each of the last three years, culminating in 3.6 walks per nine innings last year. So his control is down, too.

What could be the cause of this decline? To me, the most obvious answer is wear and tear somewhere in his joints. Ever since he came into the league, the talking heads have been speculating as to the stress his unusual motion puts on his arm. This, combined with his much-publicized roller coaster ride of weight gain and loss, could be taking its toll finally.

This would not only explain his decreased velocity, but his desire to stop throwing his slider, which he hasn’t used at all so far this season. Until this year, he had been using the slider more often each season, which, if it was in fact hurting his arm, could explain why this decline in performance seems progressive.

One thing’s for sure: If he’s having elbow problems, he’s not doing anyone any favors by continuing to pitch with an injury. But this is all just speculation.

I obviously don’t expect LIncecum to maintain an ERA of 12 throughout the year. But if he keeps getting worse, the Giants may have to decide to address the problem somehow, or trade him and make it someone else’s concern.

Alex Grotewohl can be reached at [email protected].