While they don’t show up too often, extensions are one of the more interesting and “cool” components of Scrabble. Players like the aspect of playing long words, and associate a link between word length and stronger anagramming skill and vocabulary.
Sadly, in most cases, extensions are not worth the effort. Usually, extensions don’t score enough points and provide too much counterplay to be considered. However, one common exception is extensions to the opening rack, since these extensions often use the TWS square. Opening rack extensions can often be worth 50 points or more, making these plays worthwhile.
That being said, while extensions are often sweet, lucrative plays when drawn, that does *not* mean that you should fish for them, even if your fishing play has a high likelihood of success. The reason is that extensions just don’t have enough upside. Even if an extension scores, say, 54 points, that’s often just 15-20 points higher than an average turn.
And that’s assuming your opponent doesn’t block, doesn’t make an equivalent setup of their own (setups are a great way to counter extensions fishing) doesn’t make an extension themselves (they have first dibs), AND that you draw your extension (without drawing a better play). When you take all of these things into account, it means that sacrificing a significant amount for an extension is not worth it.
Fishing for extensions, just like fishing for bingos is a bad play unless you have a high likelihood of success and are sacrificing an extremely small amount to do so, and there really aren’t many better options. To illustrate why, let’s take a look at some examples of racks that some experts might choose to fish with, and why doing so is generally a bad idea.
The first thing that you need to do is estimate a worth of extensions. The approximate worth of an extension can be determined by the formula:
Probability of hitting extension x [(Score of extension) – (average points without extension) – worth of leave].
So for example, let’s say you’re looking at playing OXID at 8h keeping DIZ. This will inevitably be either blocked or taken quite often: let’s say 70% of the time, and you’ll draw the E about 40% of the time, so approximately 12% of the time you’ll get to play OXIDIZED next turn. OXIDIZED scores 81 points, the average score is about 39 after OXID, and the worth of the leave is 4, so 0.12(81 – 39 – 4) = ~ 4, meaning that the worth of the extension in that case is about 4 points.
On the opening rack, this ‘Score of extension’ number is often somewhere around 36, although it should be adjusted based on the things that you are opening immediately. On other boards, you may have to adjust the number based on the tiles remaining and openness of the board.
Unwarranted Extensions As you can see, most extensions really aren’t worth very much. In addition, there are usually many ways that extensions can lose value: they can be used or blocked, or your opponent can make other setups somewhat freely. Let’s take a look at some examples of situations where people might play an extension but it is not warranted:
EIIPRSZ (ZIP vs. PRIZE)
Here, you’re drawing to 6 tiles in the bag for MISPRIZE/DISPRIZE, which you will hit approximately 25-30% of the time. This will only be occasionally blocked. That being said, this effect is somewhat small: both plays score about 20-25 more points in average, so the extension is worth about 6 points.
However, this play does have some severe downsides. First of all, PRIZE gives your opponent much better options than ZIP for scoring, resulting in a reduction of 7 or 8 points next turn.
Second of all, you’re severely limiting your bingo potential severely by keeping IS instead of EIRS. This is substantial, especially since bingos will score more than extensions will score next turn. This alone mitigates the potential upside in drawing an extension and then some, since you’re likely to bingo an additional 15% next turn and an additional 10% the turn after. (That alone is worth about 12 points)
When you add in smaller factors (your opponent might extend the word, block DISPRIZE with PRIZER, board shape, etc.) ZIP is a significantly stronger play than PRIZE.
DEHNOWY (HOWDY vs. HONEY) Here, you are drawing 5 tiles drying to hit an E for HONEYDEW, which will happen about 45% of the time. This adds about 15 points to the expected score, so that’s about 7 more points, so the extension doesn’t even make up the difference in score between HOWDY and HONEY, not to mention the difference in leave or defense, both of which are substantial.
ENNPSXY (PENNY 8d vs. PYX) In this case, you are giving yourself 5 chances to draw an I, which will happen about 35% of the time. This gives you a play that’s about 25 points higher than average, but since you have the X and S, that amount is narrowed to closer to 12, giving the setup about a 4 point edge, which is honestly about the same as PENNY 8h (+2 and the EX setup). Meanwhile, PYX scores 4 more (negating the setup) but also has massive defensive value (approximately 8 points) while keeping a decent leave (ENNS is about -3 to SX) making PYX a stronger play.
BGIIMNX (MIXING 8c vs. MIXING 8d/8g)
In this case, you are considering sacrificing 4 points to hit the BEMIXING extension. You’re over 50% to draw the E, and BEMIXING scores 60 points, so if it was never blocked, it would definitely be worth it.
The problem is that BEMIXING gets blocked occasionally by overlaps, but more importantly it frequently just gets taken by your opponent first, with extensions such as AD, RE, UN, BE, and IM. This happens over 1/3 of the time, and scores over 50 points, leading to a huge increase in opponent’s score, making the 8c position completely impractical.
KOORRVW (VROW vs. WORK)
In this case, your options are mediocre. On the one hand, you have WORK which scores 22 but keeps ORV, but the other option scores 20 and keeps KOR.
WORK will hit an E fairly often: about 40% of the time. Your opponent has a myriad of extensions, that will hit about 20% of the time, but also will block a decent percentage of the time with parallels over WO: not too often, but more than usual in marginal situations. In addition, your opponent can also make setups in this position, since they know that you have three tiles that are kind of confined to the setup, and that strongly negatively affects your play. (In CSW, they also have AWORK#, completely ruining any semblance of a reasonable position). Each of these factors is only worth a few points, but combined, they accumulate to be more significant than the OVERWORK extension.
Warranted Extensions
While most extensions are not worth fishing for, some definitely are, and they are a factor that can sometimes tip the scale when choosing between two close plays. Let’s now take a look at when opening rack extensions *are* worth fishing for. As you can see, opening rack extensions are only worth while when the sacrifice is extremely small and/or the reward is overwhelming.
ACGINTX (ACTING vs. TAXING) This is a small sacrifice, since TAXING is 8 more but keeps a slightly worse leave. You’re around 50% to hit EXACTING, the A also gives you AX plays if ACTING is blocked, and it rarely will be, and even if blocked, you’re still going to have an X. The setup is worth about 10-11 points, so the 8 point sacrifice is just barely worth it.
CCKMNOS (COCK 8g vs. COCK 8h) COCKSMAN/COCKSMEN scores 57 points and is extremely likely to be drawn, allowing you to hit over 60% of the time, giving you about a 10 point increase, but since it uses the S, it’s closer to only a 5 point increase, since the average is about 45 with S plays. In this case, your sacrifice isn’t actually in points, but defense, especially the Y hook, and there’s only 2 Ys in the bag. (COCKS still gives you COCKSM_N). While this is significant and Y plays score a lot, it’s not enough to compensate for the potential upside in setup.
CENOSTZ (COZ vs. ZONES) In this case, while you’re giving up bingo potential, you’re maintaining the C which is such a valuable tile for extensions to ZONES (ECOTONES, CANZONES, and CALZONES) and scoring an additional 18 points. On future turns you can keep the Z, and the OZONES hook actually helps you get ECOZONES down, which makes the extension even more lucrative, making it very likely that you’re going to get a 50+ point play with the C in addition to the additional 18 points this turn. This pushes ZONES to be a slightly better play than COZ, but even still it’s only by a few points. In this case, the worth of the extension is more valuable, since it’s likely to be recurring.
EGINNNX (EXING 8d vs. EXING 8h) In this case, you’re only sacrificing a meager 2 points for the prospect of an A draw, which will happen over 1/3 of the time for ANNEXING. Although this isn’t a huge factor, it outweighs the 2 points that you are sacrificing.
DGIIITZ (ZITI vs. DIGIT)
In this case, DIGIT is a strong play not just because of the DIGITIZE extension, which you are likely to draw, but also because of ZIG for 33 as a strong backup play, clearing the rack. Thus, it’s not only the extension that is appealing: you also have a secondary option in addition to the prospects of the 5 tile draw. Although the extension is only worth 5 or so points, when you add in the ZIG possibility it overtakes ZITI as a potential option.
Hopefully, this guide will serve as a template for helping players understand when they should and should not play extensions, especially on the opening rack.