(CNN) First things first: The MLB on Fox theme song by Scott Schreer.

Poll of the week: A new Quinnipiac University poll finds that Republican Sen. Ted Cruz holds a 49% to 43% lead over Democrat Beto O'Rourke in the Texas US Senate race.

Cruz has led in every poll of the race taken in the last year. The average poll over the last two months has him ahead by 6 percentage points.

What's the point: Many liberals have made it a cause célèbre to try to defeat Cruz. Indeed, the attention paid to the Texas Senate race has been greater than for other more competitive races such as Tennessee, where Democrat Phil Bredesen has consistently led in polls against Republican Marsha Blackburn.

Yet the polling has continued to suggest that Cruz is ahead.

Just how much of a favorite is Cruz? We can get at this problem in two different ways. Both suggest that Democrats should keep their expectations in check.

I went back and looked at how predictive the June to July polling average was in 225 Senate races since 1998. All these races had one Democrat and one Republican on the general election ballot without a major third-party or independent bid.

Candidates in Cruz's position at this point in the race went on to win about 75% of the time.

We can also look at how experts are rating the race. CNN rates it as "likely Republican," while The Cook Political Report puts the race as "lean Republican." The Cook Political Report has been offering ratings on Senate ratings since the 1984 cycle.

Interestingly, there has been very little difference in how races rated as lean or likely at this point have turned out. About 87% of the races that lean toward one party at this point have been won by that party, while about 92% of the races that are likely to be won by a party have been won by that party.

That is, these ratings aren't perfect forecasts, though they are strong indicators. Republican Richard Mourdock, who lost the 2012 Indiana US Senate race, was the last person to lose an election that had been leaning his way at this time. He did so after making comments about rape. The last likely race to go the other way was the 2010 Delaware US Senate race. It was rated as likely Republican at this point because analysts thought Mike Castle was going to be the Republican nominee. Instead, he was upset in the primary by Christine O'Donnell, who was a far weaker general election candidate.

An average of the polling and race ratings gives Cruz about an 82% chance of retaining his seat. Interestingly, that's nearly equal to the chance implied by Dean Strachan's fundamentals-based model, which looks at factors such as the political history of Texas.

The good news for Democrats is that Texas may be moving a little bit to the left. President Donald Trump's 9-point victory in the Lone Star State was the weakest performance for a Republican presidential candidate since the 1990s. This year there are a number of competitive US House races in areas that have historically been Republican.

The problem for O'Rourke is that there is just no history of Texans pulling the lever for Democrats statewide. The last Democrat elected senator was in 1988. The last Democrat elected governor was in 1990. The last Democrat elected to any statewide office was in 1994.

Indeed, the Democratic drought in Texas is longer than it is in any other state in the entire country. Even states like Idaho and Utah, which are redder than Clifford the dog, have elected Democrats to offices like attorney general and superintendent of public instruction more recently than Texas has.

The lack of Democratic victories for these lower statewide offices is bad news for O'Rourke. We know from past elections this decade that although presidential voting patterns are most important in predicting how voters will cast ballots for Congress, they aren't the only thing that matters. Voting patterns in statewide non-congressional elections also matter.

Now, sometimes low-probability events do happen. The NFL's Buffalo Bills hadn't reached the playoffs since the 1990s. Heading into last year's regular season finale, they had a 17% chance of making the playoffs. (That's similar to the probability O'Rourke has of winning.) The Bills ended up making the playoffs on a fluke play.

Of course, most teams in the position the Bills were in don't make the playoffs. Most candidates in O'Rourke's position end up losing.