Gladwell's article looks at examples of jobs where there are few, if any, available measurements of performance available before hiring that correlate with success in the position. The performance of college quarterbacks doesn't track their success in the NFL (apparently due to factors such as the sizes of players and the types of offensive formations used), and none of the items on a resumé seem to predict the success of teachers or financial advisors.
Yet quality of teaching is a huge factor in student educational success (as I've previously noted on this blog with regard to an Economist article about a McKinsey & Co. study that compared education across OECD nations). As The Economist article I referenced noted, "Studies in Tennessee and Dallas have shown that, if you take pupils of average ability and give them to teachers deemed in the top fifth of the profession, they end up in the top 10% of student performers; if you give them to teachers from the bottom fifth, they end up at the bottom. The quality of teachers affects student performance more than anything else."
Gladwell suggests that we should find a way to hire more teachers, have them apprentice with demonstrably successful teachers, and weed out the bad ones. But the most successful nations do not follow Gladwell's suggestion of increasing the number of new teachers, instead doing nearly the opposite. Again quoting The Economist:
Nor do they try to encourage a big pool of trainees and select the most successful. Almost the opposite. Singapore screens candidates with a fine mesh before teacher training and accepts only the number for which there are places. Once in, candidates are employed by the education ministry and more or less guaranteed a job. Finland also limits the supply of teacher-training places to demand. In both countries, teaching is a high-status profession (because it is fiercely competitive) and there are generous funds for each trainee teacher (because there are few of them).
South Korea shows how the two systems produce different results. Its primary-school teachers have to pass a four-year undergraduate degree from one of only a dozen universities. Getting in requires top grades; places are rationed to match vacancies. In contrast, secondary-school teachers can get a diploma from any one of 350 colleges, with laxer selection criteria. This has produced an enormous glut of newly qualified secondary-school teachers—11 for each job at last count. As a result, secondary-school teaching is the lower status job in South Korea; everyone wants to be a primary-school teacher. The lesson seems to be that teacher training needs to be hard to get into, not easy.
Gladwell's suggestion of apprenticeship, however, fits with the McKinsey & Co. study suggestion of improving teacher training and encouraging good teachers to share information and lesson plans with each other, as well as having top teachers provide oversight to teacher training.